Tuesday, January 21, 2014

The normal thickness of the uterine wall during pregnancy

In his trial testimony, Dr. Brian Peterson said this about Laci's uterus as he observed it during the autopsy.

PETERSON: Sure. The uterus, in the first place, from the lowest portion of the uterus where it connects to the vagina, to the uppermost portion, the fundus, measured 23 centimeters. That would be roughly ten inches. As I said, normally, a uterus in the non-pregnant state may be the size of a golf ball. So an inch and a half or so. In greatest dimension, this is substantially larger. In the non-pregnant state, the uterus is almost solid muscle. There is obviously a cavity on the inside of it. But just to feel it, to make a section across, it is a relatively solid muscle. This uterus was markedly thin. The thickest, and I measured the wall of the uterus in several locations. The thickest was two millimeters, very small, all the way to nothing. Up near the top of the uterus it actually been, to my eye, abraded, and was open. So up there there was no wall. So the thickness of the wall ranged from nothing to two millimeters. So, in summary, what we have is a uterus that's much larger than a normal, non-pregnant uterus. The wall is much thinner. And as I put those two things together, I determined that that had been a pregnant uterus.

And then later he said,

PETERSON: Well, in terms of why it was the uterus there, perhaps, and other organs weren't, smooth muscle organs like the uterus in a woman, and the prostate gland in a man, tend to be relatively protected down in the pelvis, relatively resistant to degradation. So oftentimes there could be a lot of other parts missing, we'll still have that to help us determine the sex of the person. I guess that would be the main forensic significance. As I said, my other conclusion, based on the uterus, because it was enlarged and was thin, it had been pregnant. Now, at the point that I got this body, there was nothing left in the uterus. So there was no baby in there. There was no placenta in there. But the uterus remained enlarged from having been pregnant.

What he does not say is how thick a pregnant uterus normally is, especially at 32-33 weeks, Laci's stage of pregnancy on December 23, 2002.  The Defense team, and subsequently the jury, had no way to digest the information that the uterus wall was thin, 2mm at the thickest, because it had nothing to compare it to. 

I found a 1998 study that provides the information the Jury needed to draw a correct conclusion about the thinness of the uterine wall.  "Myometrial Thickness in Pregnancy: Longitidunal Sonographic Study",  is a study using ultrasound to measure the thickness of the uterine wall in 28 patients at different times during the course of their pregnancies.  These were normal pregnancies.  No difference was noted between women in their first pregnancy or in multiple pregnancies.  Laci was in her first pregnancy.  Average age of the women was 28 years, with the range from 19 to 41 years.  Laci was 27 years old.

Figure 3

Uterine wall thickness (in mm) during pregnancy. The continuous line represents the mean and the dashed lines represent the upper and lower 95% confidence intervals.  A, Anterior lower segment; B, mid-anterior wall; C, fundal wall; D, posterior wall; E, right wall; F, left wall. 
Click on the chart to enlarge it.  If you still have trouble reading it, here's a summary in data form. 

A:  7.4 mm with a standard deviation of 1.8 mm
B:  9.13 mm with a standard deviation of 1.6 mm
C:  9.48 mm with a standard deviation of 1.5 mm
D:  10.06 mm with a standard deviation of 1.9 mm
E:  8.95 mm with a standard deviation of 1.6 mm
F:  9.05 mm with a standard deviation of 1.5 mm

There's a substantial difference between the thickness of a normal uterine wall during pregnancy, and the 0-2 mm thickness of Laci's.

Dr. Peterson should have provided this information in his autopsy report, and Mark Geragos should have consulted an expert to see what it meant.  If it makes a difference in Scott's favor, as I suspect it does, Scott was entitled to have that information presented to the jury. 

If Dr. Peterson wasn't familiar with the subject, he should have done some research.  He had time between when he did the autopsy and he completed his report. 


Darth Cthulhu said...

Not sure where else to address this; but you do realize that Scott Peterson, through his defense team, concedes that Laci & Conner did in fact wash up on shore? Read 2-25-05 Defense Motion for a New Trial, page 11, first to lines under heading "B" titled by the defense: BACKGROUND FACTS - "On or about April 18, 2003, both her body and that of the baby washed up on the shore of the San Francisco Bay." published here under Documents.

Unknown said...

What about the woman that washed up later missing head and same body parts as Laci? What about all the other missing pregnant women from1999-2002 within 80 miles of their home?

Marlene Newell said...

Darth, sorry I missed your comment. If defense attorneys were always right, then there could be no appeals based on inefficient counsel . It's not Scott that conceded anything at trial, it was his attorney -- Scott may or may not have agreed with it. Besides that, are errors never to be corrected? I think that would pretty much rule out appeals, wouldn't it?

Marlene Newell said...

Angela, I don't understand your point?

Darth Cthulhu said...

But this IS the appeal! It is quite common for death row convicts to pour over their appeals with an eye for detail. I find it somewhat disingenuous for you to insinuate that Mr. Peterson had nothing to do w/ this appellate doc. Sorry, just doesn't pass the smell test. Death Row inmates on the whole, certainly the ones hoping for a favorable appeal outcome, are intimately familiar with their file. Just common sense. I am not speculating on his guilt or lack of guilt; but it is telling that the appeal document directly refers to it as a fact. On the other hand, perhaps you are right & Mr. Peterson is having his attorneys prepare a a literal life & death appeal but he just can't be bothered to provide any input & has complete trust in his attorneys to handle his life & death affairs. I await "The appeal of Mr. Peterson's appeal"; or at the very least a statement of protest from him to the court that they have an essential, "disputed" fact of the case wrong. Truly not trying to troll you; and it was shocking for me to read that in the appeal. I know if I was in his position I would be raising high hell about it if it truly was an error on my attorney's part. Just something to consider.

Marlene Newell said...

Darth, the Motion for a new trial is not the appeal. The Direct Appeal does not deal with new evidence -- and the information about the normal size of the uterine wall would be new evidence, because it was not presented at trial. And you are assuming that Scott himself was even aware during his trial that there was significant evidence that Conner did not wash ashore. That evidence only came to light after numerous field trips to the site, which also would be new evidence because it was not presented at trial and thus cannot be part of the Direct Appeal. It's very difficult to carry on a conversation here, so please join our Facebook page at https://www.facebook.com/groups/1386100825048069/