Talk:Clinical cases/Case 2

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EDD confirmed by ultrasound? But per the case story, she presented at 34 weeks. Ultrasound estimation of EDD so late in the pregnancy is rather inaccurate. Poor practice.

Was the initial ultrasound exam transabdominal? Grading of the quiz implies that this is assumed to be the case. A vaginal ultrasound may well spot a large pelvic mass. Such a large pelvic mass should be pretty easy to spot even on transabdominal ultrasound.

It is a bit hard to believe a pelvic mass of this size would be missed during the woman's annual pelvic exam.

Also, this case study seems to presume that the mass is ovarian; there are other possibilities.


 * The ultrasound to confirm dates was an early pregnancy scan, I've changed the text to clarify that. The cyst was actually very big but nonetheless missed on previous scans and examinations. This woman probably didn't have annual pelvic examinations. Indeed there were multiple possibilities, first she was thought to have a fibroid but it turned out on laparotomy to be an ovarian cyst, pathological examination is pending.--Steven Fruitsmaak (Reply) 12:18, 16 November 2007 (UTC)

Language
Must the material be phrased in medical jargon? Also "presents" means the patient is a new patient. As written, the lead-in gives the idea that this woman has had no prenatal care prior to 39 weeks. The student is promptly confused. --Una Smith 20:33, 24 June 2008 (UTC)


 * Don't know if jargon should be avoided here as this material is directed at medical students or doctors.
 * Changed "presents". --Steven Fruitsmaak (Reply) 22:07, 24 June 2008 (UTC)

1a
1. a) In general, which of the following are possible causes

"Possible" seems too broad. Doesn't the class of possible include obesity? And possibly others? I think what is really intended here is Which of the following have been known sometimes to cause. Also, to make this more useful as a learning exercise (more than a quiz), I recommend linking from each of the conditions to the relevant Wikipedia page. --Una Smith 20:33, 24 June 2008 (UTC)


 * I've removed "possible". Obesity does not cause transverse lie. You can add other options if you know any or want to add more distractors.
 * Wikilinks added. --Steven Fruitsmaak (Reply) 22:08, 24 June 2008 (UTC)

1b
possible cause is most likely to have been overlooked on a recent previous ultrasound scan

Reading this one, my overwhelming thought was it depends on who did the scan. I guessed the answer being sought was "pelvic mass" but I think placenta previa is far more common. By the way, late in pregnancy an ovarian mass will not necessarily be found in the pelvis. Finally, the question does not admit the possibility that the transverse lie is idiopathic. An unstable lie at 39 weeks is unusual but not unheard of and frequently the baby ends up in the ideal position for delivery without help from anyone else. --Una Smith 20:33, 24 June 2008 (UTC)


 * I've added an explanation about who did the scan. The point is that someone who knows obstetric ultrasound specifically looks for placenta previa but might not be so familiar with pelvic cysts. --Steven Fruitsmaak (Reply) 22:10, 24 June 2008 (UTC)
 * A routine scan would include locating the placenta. However, when there is a specific concern such as this, the scan should not be a routine one.  --Una Smith 03:57, 25 June 2008 (UTC)
 * The concern only arose late in the pregnancy, before that the scans were indeed routine. The final scan by the consultant, when a cyst was suspected, clearly demonstrated it.--Steven Fruitsmaak (Reply) 12:04, 25 June 2008 (UTC)

On vaginal examination
At 39 weeks?! I guess this patient in fact did not get any prenatal care prior to 39 weeks. She should have received a thorough vaginal exam during the 1st trimester, around the time of her "dating" US. This case needs to get its story straight. Pelvic masses are rare, and pelvic masses that grow rapidly are rarer still, and these are rarer still in adults. --Una Smith 20:56, 24 June 2008 (UTC)


 * A soft cyst is likely to have been missed by earlier VEs. Nevertheless I agree it is quite spectacular that this was discovered so late. The teratoma was probably there all the time but nobody noticed until the transverse lie complicated things. --Steven Fruitsmaak (Reply) 22:13, 24 June 2008 (UTC)

Size of mass
10 cm is a relatively small pelvic mass, and this one is soft. It should present little risk for a vaginal delivery. However, vaginal delivery presents a risk for the mass: it could rupture. A planned C section is appropriate, but not quite for the reason stated. Also, "cyst" needs to be disambiguated more clearly than it is here; most ovarian cysts are benign, are transient, and do not require surgical removal. --Una Smith 20:56, 24 June 2008 (UTC)


 * I agree that it might be small for a pelvic mass, but given the fact that 10 cm is roughly the narrowest part of the birth canal and that the transverse lie probably means that there is a significant obstruction, I don't think vaginal delivery can be risked. Soft on palpation does not mean it would allow passage of the newborn. --Steven Fruitsmaak (Reply) 22:15, 24 June 2008 (UTC)


 * If a soft 10cm pelvic mass can cause transverse lie, then a pound or two of fat in the presacral space can do the same. Conversely, if obesity cannot cause transverse lie (as claimed above), why should this small mass cause it?  To me, this sounds like a case of investigation of one possible problem finding another, unrelated problem.  Correlation does not prove causation. --Una Smith 03:53, 25 June 2008 (UTC)


 * Neither the Oxford Handbook of Clinical Specialties nor UpToDate mention obesity as a factor causing transverse lie, whereas tumors are a known cause. Of course it's impossible to ensure that there is a causal relationship here, but I don't think many obstetricians would risk vaginal delivery in this context. --Steven Fruitsmaak (Reply) 12:08, 25 June 2008 (UTC)
 * Case reports involving obstructed labor and subsequent discovery of a maternal tumor typically involve tumors far larger than 10cm. I think the case report has to examine the unknowns, not just the narrow line currently drawn between facts and inferences.  A cynic would say of course an obstetrician would prefer a C-section.  Never forget they are surgeons. --Una Smith 21:18, 25 June 2008 (UTC)

Surgery cures
This case echoes a blind spot in the OB/Gyn literature, shared with many other surgeons: namely, that surgery cures. This case merits consultation with an oncologist familiar with germ cell tumors, and tumor marker blood tests, preferably before the cyst is touched by a surgeon. --Una Smith 20:56, 24 June 2008 (UTC)

Case discussion
The case discussion is fundamentally unsound. Yes, malignant germ cell tumors are much rarer than their "benign" sister, Teratoma. However, if the pelvic mass is a malignant germ cell tumor, then treating it as if it is benign is a serious error. The German germ cell tumor study group (MAKEI) makes two key points: (1) about half of all pediatric germ cell tumors that are malignant are classified at the time of initial surgery as benign (they are found to be malignant when the child has a recurrence), and (2) recurrence of malignant tumors is most highly correlated with surgical technique. The ovarian cancer literature is full of studies about this problem, in girls and women: if an ovarian mass is a malignant tumor then it is very important to remove the tumor completely intact, without spillage, and without fine needle aspiration of any contents for analysis. Blood tumor markers may be used to help decide in advance of surgery whether to simply remove the ovary, without any attempt at dissection of the mass. Many women, if given the choice, choose to have the ovary taken out. Period. Others want to preserve every iota of reproductive potential. Personally, I would rather cut out an ovary than go through chemotherapy. --Una Smith 21:19, 24 June 2008 (UTC)


 * I don't exactly see where the discussion contradicts what you say: are you referring to the final sentence? Please clarify or boldly go ahead and change things in the case discussion. --Steven Fruitsmaak (Reply) 22:17, 24 June 2008 (UTC)