Acute abdomen pathology Flashcards
Twisted ovarian cyst: underlying pathology
- the cyst within the ovary is attached by a pedicle of blood vessels which becomes twisted thus increasing the pressure
- first venous blood flow is obstructed then over time with further twisting arterial supply can also be affected
- decreased venous return leads to congestion as blood is still being pumped in
- the ovary becomes haemorrghagic but also necrotic because even though blood is coming in it’s not well perfused
- generally underlying pathology is in the ovary
Twisted ovarian cyst: causes
- mature cystic teratoma
- lesion
Mature cyst teratomas
Mature vs immature teratoma
Where do most ecotopic pregnancies occur?
Fallopian tube (90%)
Causes of ectopic pregnancies in the fallopian tube
- 50%: identifiable lesion such as chronic salpingitis from pelvic inflammatory disease, or adhesions from appendictis, endometriosis, or previous laparotomy
- 50%: no cause can be identified
How does chronic salpingitis cause ectopic pregnancies?
- chronic salpingitis- inflammation of the fallopian tubes
- generally the fertilized ovum would travel to the uterus but the inflammation of fallopian tubes impairs its movement so it gets implanted in the fallopian tubes instead
- the fertilised ovum grows within the narrow tube–>tube bursts–>haemorrghage
How common is ectopic pregnancy?
1/150 pregnancies result in ectopic implanation.
but most can’t survive in extrauterine environments- except if it’s in the fallopian tubes.
Most common complication of ectopic pregnancy in fallopian tube
- fallopian tube bursts–>haemorraghe
- often 6 week safter previous menstrual period
Clinical presentation of ectopic pregnancy
- normal sympoms of pregnancy- morning sickness, amenorrhoea, swollen breasts, positive pregnancy test
- intermittent lower abdominal pain before sudden onset severe pain
Mechanisms and causes of intestinal obstruction
- WITHIN LUMEN- eg Meconium ileus (in children with CF)
- WITHIN WALL- eg Tumours eg Adenocarcinoma
- EXTRINSIC- eg Caecal volvulus
What is meconium?
The earliest stool of the infant consisting of material they’ve ingested while in utero. Expelled after birth
What is meconium ileus?
- occurs in children with cystic fibrosis
- children may be born with meconium ileus due to the viscid consistency of the meconium in CF
- the viscid nature of meconium leads to obstruction
- in later life they develop meconium ileus equivalent (MIE) sydrome
(UNIQUE TO CF)
Colonic adenocarcinoma
- forms in an annular ring like fashion around the bowel wall
- leads to constriction and ultimately obstruction
Colonic adenocarcinoma histology
What is volvulus? Which part of the GI tract does it occur in?
- Twisting of the bowel
- In adults, it cccurs with equal frequency in the small intestine (around a twisted mesentry) and colon (around sigmoid or caecum which are more mobile)
**it’s not the mesentry that twists around the bowel, it’s the bowel that twists around itself and the mesentry**
- In children (less common) it occurs mostly in small intestine
- results in ischaemia and the buildup of gas and fluid in the portion of bowel affected
- ultimately can result in necrosis or gangrene
How do you treat volvulus?
-requires immediate surgical intervention
Presentation of volvulus
- abdominal pain
- distention
- COMPLETE constipation
Clinical presentation of intestinal obstruction
- abdominal pain: true colic is intermittent central gripping pain.
a) small bowel: every 2-20 minutes
b) large bowel: every 30 minutes - vomiting
- distention
- absolute constipation
What is an abscess?
Localised area of necrosis (walled off)
Pathophysiology of acute appendicitis
- FAECOLITH (hardened stool) blocks the lumen of the appendix
- the appendix then CONTRACTS to try and push the faecolith out
- this increases the PRESSURE within the bowel wall
- increased pressure leads to ISCHAEMIC CHANGES–>lack of blood flow to the wall–>increased susceptibility to bacterial infections which then causes inflammation
- common organisms: E. Coli, Streptococci,
Describe the pathological progression of appendictis
- earliest lesion superficial ulceration of the mucosa (if it’s more extensive then it can lead to necrosis)
- ischaemic processes further away from blood supply are more serious
- interference with circulation leads to necrosis and perforation which can spread to the peritoneal cavity
- if infection becomes walled off it can lead to a LOCALISED ABSCESS. This can then spread leading to generalised peritonitis (which you wanna avoid)
- ulceration stops at mucosal surface
- symptoms associated with obstruction are poorly localised, pain associated with peritonitis differ
Where does ulceration of the appendix occur?
Only at mucosal surface