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Try Vaginal-Perianal GBS Cultures


 

From the Annual Meeting of the American College of Obstetricians and Gynecologists

Major Finding: More than half (60%) of women reported no pain with the vaginal-perianal method, compared with 18% with the vaginal-rectal method. The sensitivity and specificity of the vaginal-perianal method were 91% and 99%.

Data Source: A study of 200 women at least 18 years of age with an average gestational age of 35.9 weeks.

Disclosures: Dr. Trappe reported that she had no relevant financial disclosures.

WASHINGTON – Vaginal-perianal cultures for group B streptococcus may be a more comfortable option for pregnant women and have comparable accuracy to vaginal-anal cultures, a study of 200 women has shown.

“Vaginal-perianal cultures may be a reasonable, patient-preferred alternative for the recommended vaginal-rectal cultures of GBS during pregnancy,” said Dr. Karen L. Trappe of Riverside Methodist Hospital in Columbus, Ohio.

It's estimated that 10%–30% of pregnant women are colonized with GBS, which is an established cause of neonatal morbidity and mortality. In 2002, the Centers for Disease Control and Prevention advised universal prenatal screening and the American College of Obstetricians and Gynecologists published a committee opinion outlining the collection of GBS cultures between 35 and 37 weeks' gestation (Obstet. Gynecol. 2002;100:1405–12). GBS cultures are to be obtained by a swab of the lower vagina (vaginal introitus) followed by the rectum (insert swab through anal sphincter). This collection method was based on a 1977 study suggesting that the GI tract was the primary site of GBS colonization. However, vaginal-anal cultures are uncomfortable for patients.

Dr. Trappe and her coinvestigators studied whether vaginal-perianal cultures were equally effective in identifying GBS and were more comfortable for patients. They included women in the study if they were at least 18 years old, were to undergo routine GBS culture, and spoke English, Spanish, or Somali. The researchers collected data from 200 patients. The average maternal age was 26 years, and the average gestational age was 35.9 weeks. In terms of ethnicity, half (49%) of patients where white, followed by black (23%), Hispanic (14%), Asian (1%), and other (13%). Although inclusion criteria were for 35–37 weeks' gestation, seven women outside of this range were enrolled – three at 34 weeks', three at 38 weeks', and one at 39 weeks' gestation.

The vaginal-perianal specimen was collected first, followed by the recommended vaginal-rectal specimen. Women were asked to rate pain on a 0–10 scale for each collection method. They also were asked if one method was more uncomfortable than the other. The overall agreement rate between the two collection methods was 96.5%. The sensitivity and specificity of the vaginal-perianal method were 91% and 99%.

“Patients also reported statistically greater pain and discomfort with the vaginal-rectal culture collection, with over two-thirds of patients reporting less discomfort with the vaginal-perianal method,” Dr. Trappe said at the meeting. More than half (60%) of women reported no pain with the vaginal-perianal method, compared with 18% with the vaginal-rectal method. “Patients indicated a preference for the vaginal-perianal collection method based on pain and discomfort surveys,” she noted.

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