Obstetrics- Q&A- Series I

Question 1: A 21 year old female presents to the OPD. She is pregnant and when asked, states that the first day of her last menstrual period (LMP) was on February 02, 2008. It was a Sunday. Calculate her expected date of delivery (EDD).

Answer: November 09, 2008.

Pregnancy is calculated using the first day of the LMP, not the day of conception. The average pregnancy is 280 days (40 weeks) which helps us to calculate the EDD. This is done by taking the date of the LMP, counting forward by 9 months, and adding 7 days. The day of the week has absolutely no significance. Keep in mind that this calculation is assuming that: the length of the cycle is 28 days long, ovulation occurs on the 14th day, cycles are normal.



Question 2: The above patient is examined and upon palpation, and increased Symphysis-Fundal Height (SFH) is noted. What are some possible causes for this increase?

1. macrosomia (big babies)
2. multiple pregnancies
3. polyhydramnios
4. all of the above

Answer: (4) All of the above can cause an increase in SFH.

The SFH is measured by palpating the fundus of the uterus and the upper border of the symphysis pubis. The distance between the two should be measured in centimeters. In general, the fundal height is usually approximately 2 cm less than the number of weeks of pregnancy. A decrease in SFH signifies Intrauterine Growth Restriction (IUGR) or oligohydramnios.

Question 3: 18% of women believe that a pelvic examination can cause miscarriage, and at least 55% find it an unpleasant experience. With that said, in which circumstances is a vaginal examination absolutely necessary?

Answer: 1- excessive or offensive discharge. 2- vaginal bleeding (in the known absence of placenta praevia). 3- to perform a cervical smear. 4-to confirm rupture of membranes.

Question 4: In what conditions are a digital examination contraindicated?

Answer: 1- known placenta praevia or vaginal bleeding when the placental site is unknown and the presenting part is un-engaged. 2- prelabor rupture of membranes (for risk of ascending infection).

Question 5: A 33 year old female, gravida 3 parity 2 presents to your clinic with edema. Fluid retention accounts for 8-10 kg of the average maternal weight gain of 11-13 kg. Where is this fluid located?

1. placenta
2. growing fetus
3. intracellular compartment
4. extracellular compartment
5. 1, 2, and 4
6. 3, but mainly 4

Answer: (6) There is some increase in intracellular water, but the most marked expansion occurs in extracellular fluid volume.

Factors contributing to fluid retention are: Sodium retention, Resetting of osmostat, Decrease in thirst threshold, decrease in plasma oncotic pressure.

Question 6: What are some consequences of fluid retention like that in the above/previously described patient?

Answer: There are marked decreases in Hemoglobin Concentration, Hematocrit, Serum Albumin, and RBC Count. Increases are noted in Stroke Volume, Placental Flow, Renal Blood Flow, White Cell Count, ESR and Fibrinogen Concentration (and therefore, hypercoaguablilty).

Questions and answers were obtained in reference to: Obstetrics by Ten Teachers. Phillip N. Baker. 18th edition. 2006

Electives - Singapore Experience

Not sure really how to begin this but here I am...third year is FINALLY over. 'Finally' I write not because it seemed to go on forever - which would be a terrible thing to say seeing it was only 7 months long - 'finally' I write in a bid to really believe that the most demanding of the MBBS years is over. On more than five different occasions I thought I wouldn't make it. Not that I didn’t believe in myself, it's just the fact I could not formulate a plan to combat this monster called 3rd year.

I thought all those Pharmacology drugs would form an unbreakable barrier between me and the next phase of medicine. Toxixology nearly killed me. Pathology could have been my pick of the subjects this year but the Kodachrome unfolded so terribly in front of me that my eyes could only see my hopes of getting to year Four wiping away! In short, when you come to a big exam like this prof, you're not really sure of yourself or the exam. No doubt, a guiding plan is necessary. So anyone who comes to third year, or any year for that matter, have a plan...and better still FOLLOW it. Then cement your hard work by praying those extra prayers in addition!

Anyway the point of this article is not third year prof, the main matter of this must contain the month long electives that I just undertook in Singapore in the National University of Singapore. Having been through the process myself I figured that it would be good to give the juniors/seniors, whoever wants to pursue their electives in Singapore, a little “how to go about things” note and share the experience, seeing how the main goal of this site is to help out medical students like us all around.


First, I would like to point out that National University of Singapore is currently ranked at #3o
in the world’s top 100 universities (overall)(http://www.topuniversities.com/university_rankings/results/2008/overall_rankings/top_100_universities/ )

and at #17 in World’s top 100 universities for Medicine. (http://www.topuniversities.com/worlduniversityrankings/results/2008/subject_rankings/life_sciences_biomedicine/ )

When we hail from a school like ours, Ziauddin Medical University, it becomes essential to look out for opportunities to do electives/work on your own simply because we do not have the guidance from our institution. My friends are far sighted Alhamdulillah so we built on the foundation laid by a handful of our seniors and decided to apply for an electives program in the National University of Singapore, back in December 2007 for the session of September - October 2008. Early right? Think again. Because we got rejected.
[We applied way early so ours became a sort of ‘complicated’ case because we got rejected! Negative marks for being overly efficient!]

Task one. [Take a pen and start noting these tasks down.] Apply early! Applying for the NUS medical electives is fairly easy, all you have to do is log yourself onto the NUS website and follow instructions.

http://medicine.nus.edu.sg/clinical/

Here on it’s a simple procedure of putting down your choice of posting department (the department you’re most looking forward to working in) and the amount of time you’re willing to spend in the department/s.

You must, on the first chance, make yourself a certificate which states clearly that you are a bona fide student of ZMU and studying in ____ year. Getting this signed from the dean, I hope, will not be an issue.

Another important document we needed all along the application period was the Hepatitis B antigen test report. Get your tests done if you’re a probable for NUS electives. Looks like task number two, doesn’t it?

Having applied for the session of September/October electives we faced a slight problem in terms of our lodging. Yong Loo Lin school of Medicine, NUS’s home school of medicine, was in the middle of academic year and that meant that all the dorms were in full occupancy by the home students. We didn’t get to know this till later on so along came a haphazard search for a place to live at. We were handed a few off campus living options by coordinator of the electives program but they all turned out full too. In the end, here I should thank my friend Amena Dossul, we found a Condo in a place called Commonwealth Drive (hah, the name was as alien to us as it is to you when we heard it!)So the next task would be…find a place to live early on and preferably ON campus to save you the bus/train ride (as opposed to if you’re living OFF campus).

Desperate to find the result before leaving yet aching to join the electives program just exactly on time i.e 15th September 2008, we had a tough decision in front of us to take. The question was, to wait or not to wait? In the end we left Pakistan on the eve of 14th September 2008, hoping and praying that all should go smoothly since the result was still not out. Anyway, we were already Singapore International Airport bound.

It was a blessing that we knew some people in Singapore who picked us up from the airport and dropped us to our destination which was located at about half an hour’s drive from the airport.Getting to know our town was the first thing we did, stayed together and went around looking at markets and eating spots. It occurred to us straight away that the place we were staying at was one of the many hubs of student lodgings that are present all over Singapore. And then we visited our town’s Train station, it’s called an MRT station…remember the name because it’s one of the most used words of mine in the month I spent in Singapore. Singapore could be Asia’s very own London in terms of the efficacy of the city-wide trains except even better because the stations are newer and prettier!

Monday 15th September 2008 –First day.

Report to Ms Pushpa, the coordinator of the Special Electives Students, at 9 AM for a meeting. It's already 9 30 and we're stranded in the middle of the gianormous NUS, not knowing where the medical school buildings were…was not our fault really. But yes we got lost. The first time we all walked in the working class of the country and thanks to getting on one wrong bus, lost we were! I suppose the only good aspect of the getting lost bit was getting a good work out early morning… walking and walking till finally finding.But I guess in the meeting that followed we redeemed our status and reputation with Ms. Pushpa. Apart from the six of us, who were clearly overpowering the conference room, there were four other medical students two of whom were from Malaysia and the other two from Oxford University, England. After the meeting we were installed at our respective departments in National University Hospital (NUH) with clear instructions to report to our supervisors, most of whom were registrars in the department.The hospital is never my favorite sight. Sure, I am becoming a doctor but blood still evokes childlike disgust in me, very clichéd but the feeling is terrible, really. To see pain brings sadness to me. But what makes me go on is that someday I can, we can, help those in pain by His guidance and mercy insha'Allah. May our Lord bring health to all those who are sick and healthy. (ameen)

So naturally, as we were entering NUH I was a bit apprehensive.NUH, in the first glance, seemed to comprise of food, busy people and the famous Seven Eleven. Really. That’s my first impression of the hospital where the heart of the main lobby has an extensive food court. Then there are these green couches by the reception side which collaborate to present themselves as a rather comfortable sitting area surrounded by ATM machines. Mind you, these very green couches could become your favorite place to be at during your stay at NUH…it became ours.

NUH is clean, like a hospital ought to be… my second observation from the entrance door.Later on I looked up and found various boards guiding me to where I had to be, the Cardiology Department.

"Find lobby lift 5 and take it to floor number 3, follow the medicine wing and then end up at the cardio one." Tada, the coordinator's instruction was ringing in my ears. I followed and found my destination.The feeling in my gut became sublime suddenly, even though I was fasting and I felt my mood loop to the happier side as every step I took towards the Cardio department.

The glass door to the entrance of the Cardiology Department aka the Heart Centre is flanked by a huge model of the Heart on one side and it mimics the propagation of the action potential by lights. It's quite a sight really but all that troubled me seeing it was that I didn't remember my pathways of the Action potential correctly.Being a Cardiology enthusiast from the beginning, the inside of the Cardiac centre was everything I expected it to be yet more. Sure it was very different than anything I’d seen back here in Pakistan but this was definitely a very welcoming change of sight. The kind of people I interacted were, alhumdulillah, very guiding and helpful. What makes me smile till this day is that every word they speak, from the Chief to the PNs, they all have a wonderful little smile to offer you at the end! It’s makes you wonder, oh wow, they are happy. These are ordinary people but they are happy people. It just lightens up your day.

Over the course of the rotation I can say I, Alhamdulillah, not only learnt about but also saw a lot of Cardiology procedures. On a daily basis I was expected to turn up for rounds of the General Cardio wards at 7 am and be there shadowing the my Supervisor check the admitted with the patient till about noon. Ward 63 and Ward 64. Patients exhibited diverse range of complaints from a simple risk of Myocardial Infarction to post-bypass care in these wards. So the rounds are quite an eye opener on how to manage these cases.

This is followed by a quick lunch break but when you are fasting, you’re obviously not eating. So this little ‘lunch break’ initially comprised of me finding my friends on the green couches and sleeping with them for an hour or so amongst fifty something patients. Ofcourse we were spotted, six girls in labcoats sleeping in the middle of the hospital waiting are, like pieces of dominoes tumbled upon each other...it was not a sight you could have easily missed. So it was not a surprised when another elective student turned upto to me and said,

"I think I saw you yesterday, it's not just you..there's five more right? And you guys are usually resting in the lobby downstairs?" Ouch.

In the second half of the day usually, I was able go to an see the ongoing Invasive Cardiology procedures in different areas of the hospital. As an electives’ student you are entitled to go into the Labs and see various procedures going on…ECGs, ECHO cardiograph, Trans esophageal ECHOs, Angiogram/Angioplasty, Treadmill Stress Test/Nuclear Test and Electrophysiology. NUS has quite a reputation when it comes to research so I wasn’t surprised when I witnessed a number of clinical trials taking place on newly researched drugs for Arrhythmia and Pulmonary Hypertension. Also undergoing Clinical Trials is very interesting software which enables patients to record their 24-hours ECGs in their mobile phones. Not to sail under false colors of being proud BUT BUT BUT...I did get that mobile ECG tested upon myself. I think I had tachycardia just by the thought of finding out that I had a heart conduction disease!

On other days, I decided to take clinics with the Consultants and get a grip on how things go on in a private clinic. All the Consultants are extremely helpful and make quite an effort when it comes to explaining what problem each patient has. Being in the clinics is tremendously helpful in learning; picking up and identifying common problems such as Murmurs (most doctors let you examine the patients chest sounds if there is an obvious finding). There’s a variety of doctors taking clinics five days a week in the morning and afternoon sessions both, so it is really your choice as to which clinic you want to sit and observe in.

When things got a little routine like in NUH, I decided to drift a bit and take my chances in trying to find things do in the Surgery department of Cardiology. The Cardio Thoracic and Vascular Surgery department turned out to be just more than a little adventure I was looking for, surgery may truly be regarded as the ‘cool’ sister of medicine. After getting a formal permission from our Chief of the Medicine Cardiology department, me and Ayesha went on to see a Coronary Artery Bypass Graft. And in this heartbeat I can tell you that the two surgeries later, I was able to scrub in and the Surgeon in the surgery! Well, assisting means a little less assisting and more like observer-with-benefits in my last phrase you see…basically I just hung around there on and cut the sutures when asked to, hold the sternum apart, work the sucking machine in the chest cavity to suck the blood out and….most importantly, hold the heart into position while the surgeon sutured the vein onto the LAD artery. Yeah, you are reading the lifeless lines and I’m still breathlessly in awe of those moments as I recall the images. Everything ceased to matter during that time, my inability to stand blood, my hypersensitivity to seeing cut-up things, my super sensitive reactions to needles…I suppose these are the defining moments in a medical student’s life. The moments we live for and that make me you make choices. Well no, before this gets more dramatically interesting let me tell you, I did not make a choice. I still do not want to be a Surgeon. ;] My fellow students Kiran and Ayesha also had their chance of scrubbing in, scoring one point above me by stitching up the leg of a patient during the surgery!

Then after much too soon and before not so long, it was time to come back home.

Having undergone a month long training, for training I may call it, at NUH has physically and mentally prepared me to face what KDLB has to offer. Maybe not mentally but I’m sure physically the long walks won’t bother me as much as they seemed to about a month and a half ago!

I hope whoever reads this does understand that taking my first electives after third year was probably the best choice I made. By the level of teaching we have had, I knew a little bit about every aspect of Cardio medicine to not feel alienated by the presence of a heart and lung machine, ECG or the drug names that the doctors kept telling the patients of.Yet I did not know a lot so I was still able to be in awe of a lot of things I saw and eventually learnt about. I will, therefore, encourage doing electives after a little clinical exposure – after third year.

But you know what the best feeling in the world is? When you see a drug, whether it is Fentanyl down the CABG patient’s central vein or simply Simvastatin being prescribed to a patient with Stroke/Heart Vessel Disease, and then suddenly...it's as if you have no problems recalling the entire Lippincott’s black and white section dedicated to that drug…you just feel…I don’t know…it’s like…you break into this wider grin no matter how many gaps you have in the teeth....and you just cannot wait to blurt out that knowledge to impress the doctor! I think that definitely has to be the best feeling ever because…you just feel…satisfied. Alhumdulillah.

Respiration

Respiration is the release of energy from glucose or another organic chemical.

Respiration includes:
External Respiration – the absorption of oxygen and removal of carbon dioxide from the body as a whole
Internal Respiration – the consumption of oxygen and production of carbon dioxide by cells, and the gaseous exchange between the cells and their fluid media.

Respiration is achieved through the mouth, nose, trachea, lungs, and diaphragm. Oxygen enters the respiratory system through the mouth and the nose, enters the lungs via trachea into bronchioles, and reaches the air oxygen interface – the pulmonary membrane between capillary and alveoli’s surface.

LAYERS OF RESPIRATORY MEMBRANE:
1. fluid lining alveoli
2. alveolar epithelium
3. alveolar basement membrane
4. interstitial space
5. capillary basement membrane
6. capillary endothelium

Enhanced rapidity of diffusion of gases across these membranes is achieved by:

• 70 meter cube surface area of lungs, containing just 60-140ml of blood per unit time
• close proximity of capillaries to alveoli

FUNCTIONS OF RESPIRATION:
1. pulmonary ventilation
2. diffusion of oxygen and carbon dioxide between alveoli and blood
3. transport of oxygen and carbon dioxide in blood and fluids
4. regulation of ventilation

PHASES OF RESPIRATION:
Inspiration – intake of oxygen. Diaphragm contracts decreasing the volume of chest cavity, so there’s more negative pressure inside it which facilitates entry of air. Rib cage elevates, sternum moves forward so AP diameter increases. Muscles involved are SCM, scaleni, anterior serrator and external intercostals.

Expiration – exhalation of carbon dioxide. Diaphragm relaxes, increasing the volume of chest cavity. Rib cage depresses, sternum moves forward, so AP diameter decreases. Muscles involved are abdominal recti and internal intercostals.

Lets now start with some real physiology

Pleural Pressure: pressure of fluid in the space between lung pleura and chest wall pleura. It remains slightly negative. Beginning of inspiration -5 cm of water, and -7.5cm of water during inspiration, it becomes more negative during the process due to expansion of chest.

Alveolar Pressure: it is the pressure inside the air inside the lung alveoli. When the glottis is open and no air is ventilating, alveolar pressure is 0 cm of water, and is called the zero reference pressure. It decreases to -1cm of water during inspiration, for about 2 seconds, sufficient for drawing in of 0.5 L of air, and rises to +1 cm of water during expiration to exhale 0.5 L of air.

Transpulmonary Pressure: it is the pressure difference between that in alveoli and that on outer surfaces of lungs. It is a measure of recoil pressure.

Recoil Pressure: it is the pressure exerted by forces that tend to collapse lungs at each instant of respiration.

COMPLIANCE OF LUNGS:
The change in volume of lungs per unit change in pressure is called compliance of lungs. Total compliance of both lungs in normal adult human being is 200ml of air per cm of
water.

Compliance is determined by elastic forces of lung tissue, and those cause by surface tension of surfactant inside the alveoli and lung spaces.

SURFACTANT:
Surfactant is a surface active agent in water, it reduces the surface tension. In human body it is secreted by type II (two) alveolar epithelial cells.

Components of surfactant include di-palmitoyl-phosphatidyl-choline (a phospholipid), surfactant apportions and calcium ions.

Functions of surfactant are:
a) prevention of alveolar collapse, by filling in them
b) holding of air within alveoli by decreasing pressure in them, which in turn is achieved by decreasing surface tension
c) prevention of development of lung edema and related complications by an overall decrease in interstitial pressure of lungs
d) filling up any irregularities in alveolar walls.

Lack of surfactant in premature babies causes IRDS (infant respiratory distress syndrome) or respiratory distress syndrome of newborn, characterized by collapse of lungs, fatal if not treated aggressively.

COMMON BRONCHOCONSTRICTORS:
1. acetylcholine(parasympathetic NT)
2. noxious gases
3. dust
4. smoke
5. infections (by irritating alveolar epithelia)
6. microemboli occluding small pulmonary arteries
7. histamine
8. slow reacting substance of anaphylaxis
9. SO2
10. Acidic elements in smog

ALTERATIONS IN Va/Q:
(Va : alveolar ventilation
Q : blood flow to lungs)

Physiologic Shunt – when Va/Q is below normal, inadequate oxygenation of blood in pulmonary capillaries occurs. It is called shunted blood. Physiologic shunt is the sum of this shunted blood and the 2% of cardiac output which normally flows through bronchial vessels and not the pulmonary vessels.

Physiologic Dead Space – when Va/Q is greater than normal in alveoli, their ventilation is said to be wasted. The sum of this wasted ventilation and that of anatomic dead space is called physiologic dead space.

RESPIRATORY HAZARDS OF SMOKING:
Smoking causes:

a) Physiologic shunt : obstruction of small bronchioles ---> blockade of ventilation in some alveoli ---> ↓Va/Q or physiologic shunt.

b) Physiologic dead space : destruction of alveolar walls ---> no blood flow to these alveoli ---> ↑Va/Q in these areas ---> wasted ventilation ---> physiologic dead space

RESPIRATORY STATISTICS:

• Respiratory rate for a normal person, at rest is 12-15times/ minute.
• 500ml air per breath or 5-6 L per minute is exchanged between the body and environment.
• 250ml of oxygen enters the body per minute.
• 200ml of carbon dioxide is excreted out of the body per minute.
• Respiratory minute volume, at rest is 6 L/min
• Alveolar ventilation at rest is 4.2 L/min.
• Maximal voluntary ventilation is 125-170 L/min.
• Work of quiet bereathing is 0.5 kg-m/min.
• Maximal work of breathing is 10 kg-m/min.
• Tidal volume (TV) is 500 ml in adult males.
• Inspiratory reserve volume (IRV) is 3000 ml.
• Expiratory reserve volume (ERV) is 1100 ml.
• Residual volume (RV) is 1200ml.
• Inspiratory capacity = TV + IRV = 3500ml
• Vital capacity = IRV + TV + ERV = 4600 ml
• Functional residual capacity = ERV + RV = 2300 ml
• Total lung capacity = vital capacity + RV

All the pulmonary volumes and capacities are 20% more in men than women, and generally greater in large and athletic people.

REGULATION OF RESPIRATION:

1.Chemical Control :
a. carbon dioxide via CSF and brain interstitial fluid H+ concentration by medullary chemoreceptors
b. oxygen and H+ concentrations via carotid and aortic bodies

2. Mechanical Control:
a. ventilatory responses to acid-base imbalance:
hyeprventilation due to ↑ concentration of H+ in arterial blood
hypoventilation due to ↓ H+ concentration in arterial blood.
Any deviations without appropriate changes in H+ concentrations may cause respiratory acidosis or alkalosis.
b. ventilatory response to carbon dioxide:
hypercapnia due to accumulation of carbon dioxide depresses CNS and respiratory centre, causing head ache, confusion and eventually coma ( carbon dioxide narcosis).
c. ventilatory response to oxygen lack:
Decrease in arterial Po2 below 100 mm-Hg deccreases respiratory rate by increasing the discharge from nerves of carotid and aortic bodies.

3. Nervous Control:
a. vagal afferents from receptors in air-ways and lungs
b. afferents from pons, hypothalamus and limbic system
c. afferents from propioceptors
d. afferents from baroreceptors

MISCELLANEOUS:
§ Dyspnea - difficult or labored breathing, when subject is conscious of shortness of breathing.
§ Hyperpnea - increase in rate or depth of breathing, regardless of patient’s sensations.
§ Tachypnea – rapid, shallow breathing.
§ Cyanosis - bluish discoloration of skin, when conc of reduced Hb in capillaries is more than 5g/dL.
§ Hypoxia – oxygen deficiency at the tissue level.
§ Atelectasis – collapse of lung alveoli
§ Pneumothorax – admission of air into pleural space.

RESPIRATORY DISORDERS:
1. Asthma – episodic or chronic wheezing, cough and bronchoconstriction.
2. Emphysema – loss of elasticity of lungs
3. Cystic Fibrosis – autosomal recessive condition, associated with impaied Na and Cl channles in epithelial surfaces of lungs and pancreas.

RESPIRATORY DRUGS:
1. Beta adrenergic agonists – for bronchodilation in asthma via beta receptors
2. Glucocorticoids – prevent inflammation by action on GRE
3. Anti-leukotrines – stop the cellular response of inflammation in asthma. Examples : Receptor antagonists -zafirlukast, monteleukast, Leukotrine blockers – zileuton
4. Mono clonal antibodies – example: xolair

Point to remember : Not to give aspirin to asthmatics because aspirin prevents the production of prostaglandins from arachidonic acid by blocking COX, hence shifting the balance to ↑ production of leukotrines from arachidonic acid by the action of lipoxygenase, which exacerbate asthma.
Aspirin should Not be given while other salicylates may be administered as aspirin Ir-reversibly blocks the enzyme, while other salicylates reversibly block the enzyme.