9.26.96 anatomy clinical correlation clinical relevance of abdominal anatomy surgical approaches to the abdomen ventral midline: most versatile ventral paramedian: slightly off the midline. commonly used in people. in veterinary medicine, is commonly a mistake. occasionally you might want to make a paramedian incision. if an animal has had a previous surgery, you might want to go off the midline, to avoid the scarred area or any adhesions. paracostal: very common in human sx, although now of course they are moving toward laparoscopic sx, but this used to be favored approach for gall bladder. tThis is an incision just caudal to last rib, paralleling the last rib. This is used in vet sx in addition to the ventral midline inc. to get better exposure to kidney or liver. flank: inc from lateral abdomen through lat obliques etc. used to be used alot 15-20 yrs ago, but is falling out of favor. Used to do cat spays this way. also c-sections in dogs and cats, since suckling isn't interfered with. this approach is very rarely used these days. note that it is important to identify the umbilicus when making abdominal incisions. when you consider the rectus abdominus sheath, the ventral and dorsal portions of the sheath cranial to the umbilicus contain similar fibers. Just caudal to the umbilicus this is not so, and as you go more caudally you see that the internal and external obliques and transversus abdominus send fibers in different ways at different times. a ventral abdominal incision allows you to place your sutures in the linea alba, but caudally, it's common to slip off the linea alba since it is so narrow. it's common to need to suture in the ventral sheath of the rectus abdominus which is stronger than the dorsal sheath in the caudal area. approach to abdominal organs is driven by the location and mobility of the organs. liver is relatively stationary, due to the two triangular ligaments which attach it to the diaphragm. Even if you incise those ligaments, liver is pretty stationary due to caudal vena cava and hepatic portal system. caudal vena cava goes through right medial and right lateral liver lobes. to approach liver you need a cranial midline ventral laparotomy. kidneys are immobile and retroperitoneal. right kidney is located in the renal fossa of the caudate liver lobe. can be hard to approach from midline - might have to add a paracostal incision, or do a flank incision. The cecum is pretty mobile. You can pull it out of any hole you make in the ventral body wall. same w/rest of most of intestines, although the duodenum is restricted by the duodenal colic ligament and the mesoduodenum which is very short. If you have to operate on descending or transverse duodenum you have to cut the duodenal colic ligament or cut a paracostal incision to gain access The spleen is pretty mobile, you can move it around a lot. The stomach is partly mobile and partly not mobile. The greater curvature and pylorus are the most mobile parts, and can in fact cause pathology because of this by rotating on the long axis of the stomach and causing a torsion. [slides- examples of laparotomy incisions] caudal laparotomy needed to get at prostate, bladder, caudal portion of colon. this is hard to do on the dog because the "willy" is in the way. So, you start normally and just deviate laterally to continue the incision of the SKIN in a paramedian plane, reflecting the skin and prepuce to the side and continuing the incision through the body wall on the midline. the caudal superficial epigastric (external pudendal branch) supplies the prepuce and the protactor prepuciae. There's also a cranial superficial epigastric coming in and you don't need to worry about preserving each thing because there is good collateral supply. you need a cranial abdominal incision also to repair a diaphragmatic surgery. when you do this, you have to ventilate the animal because you are effectively making a thoracotomy incision as well. slide of cat spay through flank incision. it is also possible to reach dorsal retroperitoneal structures through this incision, eg kidneys, adrenals. flank approach down side: might be hard to get to "other" side if doing bilateral procedure. spay isn't hard due to mobility, but adrenalectomy could be hard. it can be hard to grab a ligated pedicle of the uterus, though, if you suspect it may be hemorraghing. Exposure kind of sucks with this incision. You really want to use it on sx where you can exteriorize the organ. This lack of exposure is partly due to the fact that there's lots of stuff in there, and partly because you go through 3 thick muscles to make this incision, and these muscles tend to try to "close down" on the incision. Two ways to approach through flank; muscle cutting and muscle separating. Much nicer to do a muscle SEPARATING approach. You divide the muscles through their fibers to get in. but this does reduce visibility, and you certainly wouldn't want to do an exploratory this way! But, it's ok for a right adrenalectomy or a spay, generally. use the umbilicus as a landmark to find the midline and as a way to find an entrance into the peritoneal cavity. skin incision is made first, bleeding is dealt with, and then you are at the subcutaneous fat. bleeding can be dealt with with forceps or electrocautery. a scalpel is used to incise subq fat, until you see the linea alba. you expose the linea the full length of the skin incision. So, then, find the umbilicus again - small knot in the linea. this is a good place to enter the abdomen, because sometimes there's already a little defect there. just dorsal to the umbilicus is the fat pad and falciform ligament. caudal to the umbilicus is the bladder, spleen, intestines. so it's good to enter at umbilicus or just cranial to it, because just inside it is fat, so it's reasonably safe. you want to avoid going caudal to the umbilicus because you might cut open the bladder by accident and lose some self confidence and feel really stupid. doesn't help visualization much either. Once in the peritoneal cavity, you can insert blunt tissue forceps and push away intraperitoneal structures while cutting along the linea with the scalpel. closure of paramedian incision: if cranial to umbilicus, go through ventral and dorsal sheaths of rectus abdominus on both sides of the incision. try not to grab muscle - it doesn't add strength and could be painful. if caudal to umbilicus, only need to repair ventral sheath, because the ventral sheath is much much stronger than the dorsal in that region. once the ventral midline body wall is repaired, you reappose the subq fat (loosely tied sutures work), and then close the subdermal layer of skin w/simple continuous suture pattern, and then skin is closed with simple interrupted sutures if desired. You don't have to put in the skin sutures - esp if animal is intractable!