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#1
02-27-2012
 USMLE Forums Master Steps History: --- Posts: 1,365 Threads: 648 Thanked 591 Times in 355 Posts Reputation: 601
Calculating the Expected Date of Delivery!

A 31-year-old woman, gravida 4, para 2, abortus 1, was seen at the outpatient clinic with a chief complaint of missing her menstrual period. She had been using barrier methods of contraception. Her most recent pregnancy ended in a spontaneous first trimester loss requiring dilation and curettage. Her two previous successful pregnancies were unremarkable, resulting in spontaneous-onset labor at term, followed by uncomplicated spontaneous vaginal deliveries of healthy neonates who are alive and well. Her last menstrual period was June 10. A qualitative serum -human chorionic gonadotropin (hCG) test had positive results. Assuming her usual cycle length is 32 days, which of the following is her most likely due date?
(A) March 12
(B) March 17
(C) March 21
(D) November 13
(E) November 17
 The above post was thanked by: Ace3 (02-27-2012), Chococat (02-27-2012)

#2
02-27-2012
 USMLE Forums Master Steps History: 1 + CK Posts: 623 Threads: 62 Thanked 290 Times in 186 Posts Reputation: 300

its march 17...u add 9 mons n 7 days to last date..
#3
02-27-2012
 USMLE Forums Master Steps History: 1+CK+CS Posts: 735 Threads: 89 Thanked 289 Times in 191 Posts Reputation: 301

(B) March 17

#4
02-27-2012
 USMLE Forums Master Steps History: --- Posts: 1,365 Threads: 648 Thanked 591 Times in 355 Posts Reputation: 601

thats the catch.

guys, its wrong. -3m+7d goes if month is 28 days long. i did that too and wondered how tricky usmle can be.
 The above post was thanked by: dr.dhruvdesai (02-29-2012)
#5
02-27-2012
 USMLE Forums Scout Steps History: Step 1 Only Posts: 26 Threads: 4 Thanked 9 Times in 8 Posts Reputation: 19

21st of march ''c''. Add the extra 4 days (i.e,32-28) to your calculation...It will give you march 21.

Last edited by Josh George; 02-27-2012 at 08:00 AM.
 The above post was thanked by: dr.dhruvdesai (02-29-2012)
#6
02-27-2012
 USMLE Forums Scout Steps History: --- Posts: 58 Threads: 1 Thanked 142 Times in 19 Posts Reputation: 152

Quote:
 Originally Posted by tyagee thats the catch. guys, its wrong. -3m+7d goes if month is 28 days long. i did that too and wondered how tricky usmle can be.
You just add 4 days to the calculation (because 32 days instead of 28 days cycle).
So March 17 + 4 days = March 21
#7
02-27-2012
 USMLE Forums Master Steps History: --- Posts: 1,365 Threads: 648 Thanked 591 Times in 355 Posts Reputation: 601

Quote:
 Originally Posted by USMLEisnoteasy You just add 4 days to the calculation (because 32 days instead of 28 days cycle). So March 17 + 4 days = March 21
can u explain it further...clearly...
#8
02-27-2012
 USMLE Forums Scout Steps History: Not yet Posts: 77 Threads: 25 Thanked 108 Times in 29 Posts Reputation: 118

Quote:
 Originally Posted by tyagee can u explain it further...clearly...
Actually it's not so hard also not too easy but just Math

Mostly based on 28 days cycle, add 9 months and 7 days to LMP
so got March 17 accordingly.
March 17 just use 28 day cycle.
The woman in the quest is 32 day cycle. So more 4 days longer.
That's why just add March 17 to 4 , finally got March 21 as the final answer and chose C.
#9
02-27-2012
 USMLE Forums Newbie Steps History: Not yet Posts: 4 Threads: 0 Thanked 0 Times in 0 Posts Reputation: 10
17 march

its 17th march because 32 days is within normal range of menstrual cycle which is from 24-32 days and u just have to add 9 months and 7 days
#10
02-27-2012
 Banned Steps History: 1 + CK Posts: 751 Threads: 133 Thanked 309 Times in 192 Posts Reputation: 319

March 21 is the correct answer.
#11
02-27-2012
 USMLE Forums Master Steps History: Not yet Posts: 590 Threads: 8 Thanked 239 Times in 192 Posts Reputation: 249

(C) March 21
#12
02-28-2012
 Guest Steps History: 1+CK+CS Posts: 441 Threads: 153 Thanked 396 Times in 211 Posts Reputation: 419

Luteal phase of menstrual cycle is constant-14 days. So her follicular phase will be of 18 days and so the day of ovulation is delayed 4 days-so instead of 17 , answer will be 21st march.
 The above post was thanked by: dr.dhruvdesai (02-29-2012), Mondoshawan (02-29-2012), pass7 (02-29-2012)

 Tags ObGyn-, Step-2-Questions

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