The 1980's
Prior to the advent of high-definition obstetrical ultrasound, There was no way to diagnose monoamniotic twins, and consequently the published mortality rate was around 50%.
Then, in 1987 Dr. John Rodis published an article describing the successful management of three sets of twins.
Before I discuss the Rodis article, an explanation. A medical article begins with an "abstract" that briefly describes its findings and conclusions. This abstract is available online at PubMed, and I will include links to each of these abstracts. Unfortunately, I cannot reproduce for you the full text of these articles because they are protected by Copyright. I will, however, quote freely from them.
Also:
1. By "non-stress" testing, "monitoring," or "surveillance" I mean listening to the fetal heart rate with the monitor to look for signs of impending cord strangulation.
2. There are other precautions that monoamniotic pregnancies require (such as "biophysical profiles" to watch for cord entanglement and to see if the babies are growing properly), but for these web pages I am only concerned with how often non-stress testing should be done.
3. Steroid administration to the mother induces the fetal lungs to mature, and fetal lung maturity is the most important factor in how well preemies adapt to life outside the womb.
4. Fetal lung maturity can be directly measured by taking a sample of amniotic fluid. Thus, steroids and amniotic fluid testing are used to optimize outcomes after cesarean delivery.
5. When I say that an author "cites" a particular article, I mean that the author has included a footnote to another article to support whatever statement he is making. The author believes that his citation supports or proves what he is saying.
6. Although many of the medical articles have multiple authors, for simplicity I will only refer to the first-named author.
Dr. Rodis described three cases at the University of Connecticut.
Case 1. The mother first came to the hospital when she was already 33+ weeks. She had had no prior monitoring, and the twins were both alive -- these twins were lucky. Apparently Dr. Rodis immediately delivered the twins by cesarean section.
Case 2. Daily non-stress tests were performed beginning at 27 weeks and cesarean delivery was at 34 weeks when the lungs were mature.
Case 3. Same as Case 2, delivery at 34 weeks. There is additional information that the first amniotic fluid test at 33 weeks showed immature lungs (so they decided to wait a week before delivering). But before the results were back for the next text done at 34 weeks, the fetal monitor developed ominous signs of cord knotting. An emergency cesarean section saved both children just in time.
The abstract concludes "Intensive fetal surveillance and operative delivery should improve neonatal outcome." The article itself goes farther.
"We recommended hospitalization for bed rest and daily testing in all monoamniotic twins.... We recommend intensive surveillance from 25 until 32 weeks' gestation, after which time delivery should be undertaken."
Curiously, Dr. Rodis recommended delivery at 32 weeks, even though none of the three cases he described were actually delivered according to this protocol.
Dr. Carr reviewed the records at his Rhode Island hospital (part of Brown University) from 1967 to 1988, and he found there had been 24 sets of monoamniotic twins over that period. This series included many cases before the era of fetal monitoring and fetal ultrasound. The article makes no mention as to how these cases were managed. His main finding was that 14 of the 48 twins died before reaching 30 weeks, but that none died thereafter.
Dr. Carr's argued that if no twins died after reaching 30 weeks, there is no urgency to deliver them if they make it that far. Citing and disagreeing with 1987-Rodis, Dr. Carr asked, "What's the rush?"
But 1990-Carr disagrees with 1987-Rodis only as to the timing of delivery, and this creates a "controversy" only on that point. Dr. Carr has nothing to say about how these pregnancies should be monitored.
Reporting from the University of Iowa, Dr. Tessen reviewed his 23 cases of monoamniotic twins going back to 1961. He was specifically interested in the 1990-Carr findings, and Dr. Tessen was purportedly able to confirm that no twins died once they got to 32 weeks. The abstract reads:
"No fetal death occurred after 32 weeks, suggesting that prophylactic pre-term delivery may not be indicated in all cases."
The article itself concludes:
"Prophylactic pre-term delivery has been advocated [by 1987-Rodis], usually by 32 weeks'.... Our data suggest that this may not be helpful. We found no fetal deaths after 32 weeks' gestation, which agrees with the recent report of [1990-Carr]."
HOWEVER, there is an addendum to the article that reads:
"Since the submission of this manuscript, it has come to our attention that a double fetal death occurred at 35 weeks' gestation in a monoamniotic twin pregnancy."
A pretty important addendum that negates the entire article! And this is not the only article I will discuss where the data in the article does not support the conclusions in the abstract.
