PCOS Fluid in Anterior or Posterior Cul-de-Sac By Nicole Galan, RN Nicole Galan, RN Facebook LinkedIn Twitter Nicole Galan, RN, is a registered nurse and the author of "The Everything Fertility Book." Learn about our editorial process Updated on August 01, 2021 Medically reviewed Verywell Health articles are reviewed by board-certified physicians and healthcare professionals. Medical Reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Anita Sadaty, MD Medically reviewed by Anita Sadaty, MD Facebook LinkedIn Twitter Anita Sadaty, MD, is a board-certified obstetrician-gynecologist at North Shore University Hospital and founder of Redefining Health Medical. Learn about our Medical Review Board Print Your gynecologist or fertility specialist may report that an ultrasound has detected free fluid in your cul-de-sac area. This is an area just behind the vagina. Learn the different causes and concerns about this finding. Cul-de-Sac Anatomy There are two small pouches close to the uterus, one on either side, called the cul-de-sacs. The anterior cul-de-sac is located between the bladder and the uterus. The posterior cul-de-sac is found between the uterus and the rectum. They are also called the excavatio recto-uterina (posterior) and excavatio vesico-uterina (anterior). Another term for cul-de-sacs is pouch of Douglas, named after the Scottish anatomist James Douglas. Jessica Olah / Verywell Causes of Fluid in Cul-de-Sac Fluid in the cul-de-sac can be caused by many different factors. Sometimes fluid from a ruptured cyst or follicle can accumulate there. At other times, fluid in the cul-de-sac could indicate more severe problems. Here are some possible causes of fluid in the cul-de-sac: Ectopic pregnancy Endometriosis Following culdocentesis Gross ascites Hydatidiform mole Increased ovarian permeability due to estrogen influence Ovarian torsion Pelvic abscess or hematoma Pelvic inflammatory disease Retrograde menstruation Tubo-ovarian abscess Uterine fibroids Uterine rupture Finding in Fertility Treatment In women undergoing fertility treatment, fluid in the cul-de-sac (as seen on ultrasound) is a common finding in ovarian hyperstimulation syndrome (OHSS). If your healthcare provider suspects that you have this condition, they will likely suggest that you have an ultrasound to check for fluid and measure your ovaries, as enlarged ovaries are also common in OHSS. Usually, fluid in the cul-de-sac is not a cause for alarm but could be causing discomfort and affecting your fertility. Diagnostic Testing Transvaginal ultrasound is the procedure that is used to show whether there is fluid behind the uterus. Fluid will show up well on ultrasound. If fluid is found in your cul-de-sac and you are experiencing pain, your healthcare provider may order more advanced testing of the fluid. Culdocentesis is a procedure performed to check any abnormal fluid in the cul-de-sac area. Before transvaginal ultrasound became widely available, it was also used to detect the fluid. Now, it is used to remove fluid to evaluate. Culdocentesis involves inserting a needle through the vaginal wall to draw off a sample of fluid to analyze. A numbing agent or anesthesia may be used prior to the procedure. You will have a pelvic exam and your healthcare provider will hold the cervix with an instrument to insert the needle in the correct place. A small amount of fluid in the cul-de-sac is normal and is usually not of concern. If the fluid sample shows signs of pus or blood, the area may need to be drained. Sometimes blood can be a result of ruptured cyst or signs of an ectopic pregnancy. The presence of pus could indicate an infection caused by a tear or other conditions. The blood would need to be drained and antibiotics used to treat the infection. Frequently Asked Questions Do males have a pouch of Douglas? Yes, the pouch of Douglas in males is also known as the rectovesical pouch. It lies between the rectum and bladder. How is fluid removed from the anterior and posterior cul-de-sacs? In a woman, the fluid is removed for testing with a very thin needle that enters through the wall of the vagina. Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit 5 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Revzin MV, Mathur M, Dave HB, Macer ML, Spektor M. Pelvic inflammatory disease: multimodality imaging approach with clinical-pathologic correlation. Radiographics. 2016;36(5):1579-96. doi:10.1148/rg.2016150202 Kumar P, Sait SF, Sharma A, Kumar M. Ovarian hyperstimulation syndrome. J Hum Reprod Sci. 2011;4(2):70–75. doi:10.4103/0974-1208.86080 UCSF Health. Culdocentesis. Trenkner SW, Smid AA, Francis IR, Levatter R. Radiological detection and diagnosis of pouch of Douglas lesions. Crit Rev Diagn Imaging. 1988;28(4):367-381. Mount Sinai. Culdocentesis. 2021. Additional Reading Culdocentesis. MedlinePlus. Groszmann YS, Benacerraf BR. Complete Evaluation of Anatomy and Morphology of the Infertile Patient in a Single Visit; the Modern Infertility Pelvic Ultrasound Examination. Fertil Steril. 2016 Jun;105(6):1381-93. doi: 10.1016/j.fertnstert.2016.03.026. 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