Letters blast study linking ultrasound and autism

By Kate Madden Yee, AuntMinnie.com staff writer

June 11, 2018 -- A study published in February in JAMA Pediatrics that suggested a link between the incidence of autism spectrum disorder (ASD) and prenatal ultrasound is coming under fire by critics who are calling out the study's conclusion as oversimplified at best and inaccurate at worst

The original research, conducted by a team led by Dr. N. Paul Rosman of Boston Medical Center, claimed to find a statistically significant association between the development of ASD and one technical sonography parameter: the depth of ultrasound penetration for scans performed at certain points during pregnancy.

But this measure isn't valid, wrote Dr. Christoph Lees from the Imperial College Healthcare NHS Trust in London in a letter published online June 11, also in JAMA Pediatrics.

"The authors introduce a hitherto unheard-of index: the depth of ultrasonographic penetration," he wrote. "This has no clear biological or scientific justification. Nevertheless, they report that the mean depth of penetration of the ultrasound beam is greater in those who developed ASD than in healthy children. But depth of penetration of ultrasound is not a measure of ultrasonography exposure; it simply tells us how far the ultrasound beam reaches."

The study authors' conclusion that "further research is needed to determine whether other variables of ultrasound exposure also have adverse effects on the developing fetus" doesn't accurately reflect the data, he wrote.

"In apparent contravention of JAMA Pediatrics' guidance for reporting clinical studies of this nature, no recruitment flowchart with participant exclusion/inclusion criteria is shown, and neither a priori hypothesis, predefined primary outcome, nor sample size calculation are included," Lees wrote.

The study also drew criticism in a letter from Drs. David Somerset and Robert Wilson of the University of Calgary, who believe the study's conclusion that "greater ultrasonographic depth" negatively affects the fetus has not been proved and is a "gross oversimplification."

"The authors present no evidence that a mean difference of 4 mm in depth is associated with higher energy delivery to the fetus," they wrote. "Furthermore, clinical variables, such as maternal obesity and age and paternal age, are independently associated with ASD ... and these variables have not been accounted for. It is a shame that ... [the] study has such an alarmist conclusion in the abstract that is not supported by the study findings."

Because possible links between ultrasound and autism cause such anxiety among parents and pregnant women, it's crucial that studies are reported accurately, Lees concluded.

"In fact, this study shows that children with ASD were exposed to a shorter duration of prenatal ultrasonography and lower-energy scans than healthy children," he wrote. "These findings are reassuring. We respectfully suggest that a more accurate form of words would have reflected the study's finding than is found in the conclusion of the abstract.

BRR : New Doppler Index for Renal Artery Stenosis

POCUS helps medical students find more AAAs than surgeons

By Kate Madden Yee, AuntMinnie.com staff writer

June 1, 2018 -- With a bit of training, medical students using point-of-care ultrasound (POCUS) can identify more abdominal aortic aneurysms (AAAs) than vascular surgeons can by screening for the condition via physical exam, according to a study published online May 17 in the Annals of Vascular Surgery.

The findings not only confirm ultrasound's efficacy for this application but also suggest a new resource for AAA screening in an era when medical staff can be stretched thin, wrote the team led by Trinh Mai from the University of Ottawa.

"Screening for AAA has been found to be largely underutilized in the U.S., with only 15% of eligible and at-risk individuals receiving screening examinations," the researchers wrote. "To mitigate obstacles associated with access to screening [such as staff and device availability] ... the introduction of point-of-care ultrasound training at the medical student level, and its wide-scale implementation as an extension to physical examination, may lead to improved detection of AAA."

Ultrasound training

When untreated, abdominal aortic aneurysms have a mortality rate as high as 85% to 90%, Mai and colleagues wrote. Physical examination has low sensitivity and specificity, even when experienced physicians perform it.

Ultrasound is much more effective and is currently the primary imaging tool used to screen for the condition, but its widespread use for this application has been hindered by cost and the availability of appropriately trained technicians.

However, there's mounting evidence that medical personnel with no previous training can effectively use ultrasound to screen for AAA, especially with point-of-care ultrasound.

"The objective of our study was to determine whether a medical student, after a short training period, could reliably screen for abdominal aortic aneurysms," the group wrote. "We compared the test characteristics of point-of-care ultrasound performed by a medical student versus physical examination by vascular surgeons and a gold standard reference scan."

For the study, the researchers included data from 57 patients who presented to an outpatient vascular surgery clinic between October 2015 and March 2016 to be screened for abdominal aortic aneurysm. A vascular surgeon evaluated each patient via physical exam, followed by a second-year medical student using POCUS; patients then underwent a reference CT or vascular sonographer-performed ultrasound exam within three months of this initial screening visit.

The student had three hours of training with POCUS for detecting and measuring AAA. The training included a theoretical component led by a vascular sonographer and a practical component taught by an emergency physician, during which the student practiced ultrasound scanning under direct guidance.

After this initial training, the student practiced using ultrasound on the abdominal aortas of 60 patients with and without the condition. The student then completed a competency assessment before beginning to scan study participants, Mai and colleagues wrote.

Most of the patients (61%) were men, and the median patient age was 71. Reference exams identified 16 abdominal aortic aneurysms with a mean maximum aortic diameter of 29.5 mm. Of these, the vascular surgeon identified 11, with two false positives, for a sensitivity rate of 66.7% and a specificity rate of 94.4%. The average time to conduct the physical exam was 35 seconds.

Medical students using point-of-care ultrasound found 15 of the 16 abdominal aortic aneurysms with a mean maximum aortic diameter of 28 mm, for a sensitivity rate of 93.3% and a specificity rate of 100%. The average time to conduct the ultrasound exam was four minutes, the group wrote.

Physical exam vs. POCUS for AAA screening
Measure	Physical exam	Point-of-care ultrasound
Sensitivity	68.8%	93.8%
Specificity	93.9%	100%
Positive predictive value	81.8%	100%

All results were statistically significant.

"The results of our study, as well as several others, have proven that physical examination is relatively unreliable for the detection of abdominal aortic aneurysms," the researchers noted. "Screening for abdominal aortic aneurysms may be accurately and efficiently performed by a novice operator using point-of-care ultrasound with relatively limited training and experience."

Core curriculum?

Because point-of-care ultrasound appears to be an effective tool for identifying AAA, perhaps its use should be more formally incorporated into the medical school curriculum, Mai's team suggested.

"This study raises the question of whether we should be changing the way we are teaching medical students," the group wrote. "With the increased prevalence and use of ultrasound in medical practice, perhaps we should consider teaching focused ultrasound for abdominal aortic aneurysm detection as a standard in the medical school curriculum."

How to Perform GI Tract by Ultrasound

LINK   G I Tract by Ultrasound

Cesarean delivery changes the uterine angle

By Kate Madden Yee, AuntMinnie.com staff writer

May 30, 2018 -- Cesarean delivery can change the angle of a woman's uterus from an anteflexed one, in which the fundus faces the abdominal wall, to a retroflexed one, in which it faces the sacrum, according to a study in the May issue of the Journal of Ultrasound in Medicine

Because a retroflexed uterus can increase a woman's risk of uterine perforation during gynecologic surgery or the placement of an intrauterine device (IUD), the angle of her uterus after cesarean must be determined via ultrasound, wrote a team led by Dr. Andrea Agten of St. George's University Hospitals in London.

"Over the years, reports have associated a retroflexed uterine position with an increased surgical complication rate (e.g., uterine perforation) ... [and] although in many cases perforations are innocuous, some lead to infections, hemorrhage, and trauma to other abdominal organs," Agten and colleagues noted. "Therefore, all women with a history of cesarean delivery should undergo a transvaginal ultrasound examination before any gynecologic surgery or IUD placement" (J Ultrasound Med, May 2018, Vol. 37:5, pp. 1179-1183)

Which angle?

One of the ways the position of the uterus is assessed is by its flexion angle, which is the measure between the uterus and the cervix. Gauging uterine position is crucial for successful gynecologic procedures such as dilation and curettage, endometrial biopsy, and IUD insertion, the team wrote.

The researchers conducted the study because they had observed an increase in retroflexed uteri in their practice. And because the number of cesarean deliveries has also increased, they sought to investigate whether this higher incidence of retroflexed uterus could be caused by cesarean delivery.

The study included data from 173 patients who had undergone transvaginal ultrasound before and after either vaginal or cesarean delivery between 2012 and 2015, excluding women who had undergone a previous cesarean delivery. Two radiologist readers measured flexion angles from these exams before and after the women gave birth, and they compared them between women with vaginal and cesarean deliveries.

Of the 173 women, 107 had vaginal deliveries (62%) and 66 had cesareans (38%). The mean interval between scans was 18 months; interreader agreement for flexion angles was almost perfect, the researchers found (0.939 before delivery and 0.969 after, p < 0.001).

There was no significant difference in mean flexion angles between the uterus and the cervix for either type of delivery on antepartum ultrasound (145.8° for vaginal delivery and 154.8° for cesarean). But mean postpartum flexion angles increased significantly after cesarean, at 152.8° for women who had a vaginal delivery compared with 180.4° for those who underwent a cesarean (p < 0.001).

The change in flexion angle translated into a shift from anteflexed to retroflexed in more of the women who underwent cesarean delivery than those who had a vaginal delivery (29% versus 13%, p = 0.003).

"Our study showed that cesarean delivery can change the natural position of the uterus ... [and that it was] associated with the new development of a retroflexed uterus in one-third of our patients," Agten's group wrote.

Avoiding complications

Because a retroflexed uterine position has been associated with surgical complications, it's important for a woman's health going forward to assess the position of her uterus after she has had a cesarean, Agten and colleagues wrote.

"Cesarean delivery can change the uterine flexion angle to a more retroflexed position," the researchers concluded. "Therefore, all women with a history of cesarean delivery should undergo a transvaginal sonography examination before any gynecologic surgery or IUD placement to reduce the possibility of surgical complications.