[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Abdomen](https://durgical.com/en/anatomy/region/abdomen/) › Peritoneum [Digestive system](https://durgical.com/en/anatomy/system/digestive-system/) · [Abdomen](https://durgical.com/en/anatomy/region/abdomen/) # Peritoneum The peritoneum is the thin, smooth membrane that lines the inside of the abdomen and covers most of its organs, letting them glide against each other. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=abdomen&select=peritoneum&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The thin, smooth lining of the abdominal cavity, also wrapping many of the organs. ## What it does Lets the organs slide over each other and fights infection. Laparoscopic surgery is done by inflating this space with gas. ## Key points - Intraperitoneal organs hang on a mesentery; retroperitoneal ones lie behind the parietal peritoneum; secondarily retroperitoneal ones (most of the duodenum, pancreas, ascending and descending colon) lost it by fusion - The greater sac and the lesser sac (omental bursa) connect only through the epiploic foramen (of Winslow) - Visceral pain is referred by embryological gut: foregut to the epigastrium, midgut around the umbilicus, hindgut to the suprapubic region - A rigid, board-like abdomen with guarding and rebound tenderness means the parietal peritoneum is inflamed (peritonitis) ## Key facts **Where** Serous lining of the abdominopelvic cavity: parietal layer on the walls, visceral on organs; posterior parietal layer covers retroperitoneal organs (kidneys, ureters, aorta) **Function** Serous fluid lets viscera glide; mesenteries and omenta carry vessels; parietal layer has sharp, well-localized pain, visceral layer poorly localized ## Relations **Superficial** Extraperitoneal fat and the [transversalis fascia](https://durgical.com/en/anatomy/transversalis-fascia/) separate the parietal peritoneum from the abdominal wall muscles **Behind** Retroperitoneum: [kidneys](https://durgical.com/en/anatomy/kidney/), suprarenal glands, [ureters](https://durgical.com/en/anatomy/ureter/), aorta and [inferior vena cava](https://durgical.com/en/anatomy/inferior-vena-cava/), most of the [duodenum](https://durgical.com/en/anatomy/duodenum/), the [pancreas](https://durgical.com/en/anatomy/pancreas/) except its tail, the ascending and [descending colon](https://durgical.com/en/anatomy/descending-colon/), part of the [rectum](https://durgical.com/en/anatomy/rectum/) **Below** It drapes over the bladder, uterus and upper rectum, forming the vesicouterine and rectouterine (Douglas) pouches in women and the [rectovesical pouch](https://durgical.com/en/anatomy/rectovesical-pouch/) in men **Contents** A film of serous fluid; fluid collects in the hepatorenal pouch (Morison pouch, lowest point of the upper [abdomen](https://durgical.com/en/anatomy/region/abdomen/) when supine), the subphrenic spaces, the paracolic gutters and the pelvic pouches ## How to find it Paracentesis is usually done in the left lower quadrant, lateral to the [rectus sheath](https://durgical.com/en/anatomy/rectus-sheath/) and above and medial to the anterior superior iliac [spine](https://durgical.com/en/anatomy/region/spine/), to avoid the [inferior epigastric artery](https://durgical.com/en/anatomy/inferior-epigastric-artery/); or in the midline below the umbilicus through the avascular [linea alba](https://durgical.com/en/anatomy/linea-alba/), with the bladder emptied. ## Examination - Rebound tenderness (Blumberg sign): pain when pressure is released quickly suggests parietal peritoneal irritation - Involuntary guarding and rigidity: reflex contraction of the abdominal wall over inflamed parietal peritoneum - Shifting dullness: the dull area moves when the person turns on their side, which suggests free fluid (ascites); a fluid thrill suggests a large volume - Cough or jolt tenderness: pain when coughing or with a jarring movement suggests peritonitis ## On imaging An erect [chest](https://durgical.com/en/anatomy/region/chest/) X-ray shows free air under the [diaphragm](https://durgical.com/en/anatomy/diaphragm/) (pneumoperitoneum) after a perforated viscus; on a supine film, both sides of the bowel wall become visible (Rigler sign). Ultrasound (FAST in trauma) looks for free fluid in Morison pouch, around the [spleen](https://durgical.com/en/anatomy/spleen/) and in the [pelvis](https://durgical.com/en/anatomy/region/pelvis/); CT shows ascites, abscesses and peritoneal thickening. ## Common problems - Peritonitis: infection or inflammation, usually from a burst organ ([appendix](https://durgical.com/en/anatomy/vermiform-appendix/), ulcer); severe pain and a rigid abdomen. An emergency. ## How it is diagnosed Examination, blood tests, CT. ## Treatment - Treat the source (often surgery) and antibiotics. ## Clinical notes - Spontaneous bacterial peritonitis complicates cirrhotic ascites; it is diagnosed on fluid obtained by paracentesis - After peritonitis, pus collects in the subphrenic and hepatorenal spaces, the lowest points when lying down - Peritoneal dialysis uses the peritoneum as an exchange membrane - Tuberculous peritonitis, still seen in Colombia, causes ascites and a doughy abdomen ## Development The peritoneal cavity forms from the intraembryonic coelom; rotation of the gut and fusion of mesenteries with the posterior wall make some organs secondarily retroperitoneal. ## Memory aid Retroperitoneal organs, SAD PUCKER (English mnemonic): Suprarenal glands, Aorta and IVC, Duodenum (parts 2–4), Pancreas (not the tail), Ureters, Colon (ascending and descending), Kidneys, [Esophagus](https://durgical.com/en/anatomy/esophagus-abdominal-part/), Rectum (part). ## Related conditions - [Peritonitis](https://durgical.com/en/conditions/peritonitis/) - [Sepsis and septic shock](https://durgical.com/en/conditions/sepsis-and-septic-shock/) - [Dengue](https://durgical.com/en/conditions/dengue/) - [Ascites and spontaneous bacterial peritonitis](https://durgical.com/en/conditions/ascites-and-spontaneous-bacterial-peritonitis/) - [Familial Mediterranean fever and other hereditary autoinflammatory syndromes](https://durgical.com/en/conditions/familial-mediterranean-fever-and-other-hereditary-autoinflammatory-syndromes/) - [Major trauma (polytrauma): ATLS primary survey](https://durgical.com/en/conditions/major-trauma-atls-primary-survey/) - [Penetrating trauma (stab and gunshot wounds)](https://durgical.com/en/conditions/penetrating-trauma/) - [Blunt abdominal trauma](https://durgical.com/en/conditions/blunt-abdominal-trauma/) - [Abdominal compartment syndrome](https://durgical.com/en/conditions/abdominal-compartment-syndrome/) - [Intra-abdominal abscess](https://durgical.com/en/conditions/intra-abdominal-abscess/) ## Test yourself Think of the answer, then tap the question to see it. ## Which abdominal organs are secondarily retroperitoneal? Most of the duodenum, the pancreas (except the tail), and the ascending and descending colon: they lost their peritoneal covering by fusion to the posterior wall. ## What is the only connection between the greater sac and the lesser sac? The epiploic foramen (of Winslow). ## Where is visceral pain from the foregut, midgut and hindgut referred? Foregut to the epigastrium, midgut around the umbilicus, hindgut to the suprapubic region. ## Where does free fluid collect first in the upper abdomen in a supine patient? The hepatorenal pouch (Morison pouch), the lowest point of the upper abdomen when supine; FAST ultrasound checks it in trauma. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/peritoneum/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** peritoneum; peritoneum parietale TA2 3729 **Official Spanish (DeCS)** Peritoneo DeCS D010537 **English (TA2)** Peritoneum **Also called** peritonaeum ## Related - [Transversalis fascia](https://durgical.com/en/anatomy/transversalis-fascia/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=10727); [Anatomy, Abdomen and Pelvis, Peritoneum](https://www.ncbi.nlm.nih.gov/books/NBK534788/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/peritoneum/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/peritoneum/