Vomiting in Children (Mueller, 4/21/2021)

Many thanks to Dr. Claudia Mueller, Stanford and CPMC pediatric surgeon, for an excellent presentation on Vomiting in Children-- her lens, unsurprisingly, was on the surgical causes of vomiting in children. 

As a family medicine physician, I don't typically consider vomiting in children a "surgical" problem, but it was sure a good reminder that sometimes it is! It's a hearty crew of clinicians who want to assemble at 7:30am to talk about vomit-- but hey-I have to tell you-- her presentation was excellent!  AND the best part was that Dr. Mueller gave us a number to call if we ever run into problems. 

To watch Dr. Mueller's excellent presentation click HERE.

For the Cliff's notes version, here you go:

• Surgical causes of vomiting in children can rapidly progress to be life threatening
• Ask yourself How sick is this kid? Do they have fever, tachycardia, moist music membranes, lethargy? Can I get them to stand for the KUB?
• Presence of vomiting and ABSENCE of diarrhea is a concerning sign 
• This makes sense; most vomiting in kids is related to acute viral gastroenteritis or food poisoning, both of which should be accompanied by diarrhea. The absence of diarrhea is a sign that surgical causes of vomiting should be on your ddx
• The color of the vomit is key: color gives you some indication of the level the vomit is coming from (I know, I know, who wants to talk about the color of vomit) 
• this is particularly true in infants
• yellow/green (bilious) emesis in children <1 year is an "alarm bell that should be rung through the streets of any city" as it could be a surgical emergency (cardinal hallmark of a midgut volvulus that you do NOT want to miss)
• most children will vomit food and other particulate matter, if they vomit long enough, they will eventually vomit bile, so prolonged vomiting leading to bilious vomiting may be less concerning than it starting out bilious

• The intestine is a tube: in addition to the color of the vomit, what is coming out the bottom gives us a lot of information. If a child is having something out the bottom, they are much less likely to have true obstruction
• Passing gas is best indication (more even than bowel movements)

SBO

• Previous abdominal surgery is #1 cause of of adhesions causing SBO in children
• traumatic surgeries (e.g. trauma ex-lap) are more likely to lead to adhesions
• laparoscopic surgery maybe less risky (eg. laparoscopic appy) 
• Farting is a good sign-- air doesn't just hang out in the colon; a child that is passing gas, even if there is an obstruction, it is at least partial
• Be aware: not all kids with SBO get abdominal distention
• An UPRIGHT KUB is the imaging modality of choice to evaluate for SBO in a child
• want to be able to visualize: diaphragm, rectal gas
• UPRIGHT is super important: air goes to top, liquid down to the bottom
• air-fluid levels (straight lines) in SBO (can see in ileus, but more common in SBO)
• a sick child who cannot stand up for KUB is concerning
• CT scans can show more detail, e.g. the "point of the obstruction" but generally try to avoid CT scans in children <10 due to radiation
• if you do CT scan, should do IV contrast; used to always require oral contrast (and can be more helpful), but should be done carefully due to risk of aspiration 

Upright KUB showing SBO

• Initial treatment: NGT for decompression 
• NGT should be adequate size (if it's too small, won't work as well). An NGT an actually treat SBO by relieving the pressure
• Babies, size 10-12
• Toddlers, size 12-14
• age >7 years, size 14
• teenagers/adults, minimum size 14, better >16
• NGT has to be flushed, or it will get clogged
• If NGT is working, as evidenced by the amount coming out of NGT decreases, and child starts feeling better, you may be able to avoid surgery
• Another option after NGT: small bowel follow-through with gastrograffin (or ominpaque) can be diagnostic AND therapeutic
• 25-50cc, repeat KUB 6-12 hours after administration: decreases hospital stay either because quicker to OR vs. able to discharge home
• Hydration and serial abdominal exams are important in SBO

Midgut volvulus is the most urgent cause of bilious vomiting, usually in children <1 year old (85% before 6 months, 95% before 1 year)

• A true emergency is caused because mesenteric vein and artery get twisted, no blood flow to the entire small bowel (colon and first/second part of duodenum have their own blood supply)
• Can be life threatening in a few hours
• Perfectly healthy baby totally fine, suddenly starts throwing up yellow/green, call a surgeon!
• Imaging: UGI shows cutoff; x-ray may show just a stomach bubble (no other gas)
• Consequence so dire: lose entire small intestine, may never be able to survive not on TPN

Pyloric Stenosis typically thickening/hypertrophy of pyloric muscle fibers

• No one know why it happens
• Usually age 2 weeks to 2 months, classically first-born males
• Non-bilious (breastmilk or formula), progressive and persistent
• Imaging: ultrasound
• Surgery: cut open hypertrophic fibers, outer layer and spread it (pyloromyotomy)
• Typically does not recur

Appendicitis

• n/v, abdominal pain, umbilical down to RLQ
• renewed interest in conservative management with antibiotics only
• 95% of cases can be treated with antibiotics only, but 20% will recur in 1 year, 30% in 5 years
• fecolith has VERY high recurrence, should be operated lap appendectomy

Ileocolic intussusception

• generally age 6-36 months
• small part of small intestine gets stuck in large intestine
• usually due to laxity, lead point usually a lymph node, can be seen after enteritis OR after immunization (e.g. rotavirus vaccine)
• Imaging: ultrasound, "target sign"
• Reduction via radiology (air or contrast from anus into rectum, pushes the intussusception , reduces the small intestine), works large majority of time in kids without ischemia
• 10% recurrence rate-->  to OR
• Older kids need work up, lead point (e.g. lymphoma)

Hernias

• bilious vomiting, if incarcerated
• remember to take off vomiting baby's diaper to look for non-reduceable hernia

Small Bowel Obstruction (Sawyer 4/15/2020)

Big thanks to Dr. Russ Sawyer for an excellent presentation this week on Small Bowel Obstruction (SBO) during Grand Rounds. We are all getting better and better at this Zoom platform!

Cliff notes version of what primary care providers should know about SBO:

1. Lactate is highly sensitive for SBO (but not that specific)
2. The money is in the CT scan (CT is BOTH sensitive and specific)
• with IV+oral contrast is are ideal, but IV contrast only is probably okay
3. Many SBO patients don't need surgery (you actually can let the sun set on an SBO)
• In fact, all patients NOT acutely ill (w/fever, leukocytosis, tachycardia) deserve a trial of non-operative management
• SBO patients with a BM in last 24 hours likely will not need surgery
4. Gastrograffin challenge is an effective way to differentiate patients who may need surgery vs. those who definitely don't. 
• 90cc PO or via NGT x 8 hours in early/minimal symptom SBO (see below for details)

And now for the more robust version of my notes for those of you more in depth readers. . .

SBO is super common, >$1.5 billion per year in the US go to management of SBO

Classification of SBO

• functional (i.e. adynamic ileus)
• mechanical (acute vs. chronic, partial vs. complete) 
• adhesions (account for 80% of SBO)
• hernia (internal, groin, ventral)
• malignancy
• inflammatory disorders (IBD, ischemic bowel)

Pathophysiology of SBO

obstruction prevents people from passing food and air --> interluminal fermentation causes gas to accumulate--> bowel edema--> diminished absorption and decreased motility--> can gt transudative losses into the abdominal cavity (free fluid in the peritoneum)

Stats reminder from Dr. Sawyer, which is always helpful to review

Sensitivity: "positivity in disease" (how much you trust a positive result to mean the patient actually has that condition)

Specificity: "negativity in health" (how much you trust a negative result to mean that the patient actually does NOT have that condition).

(We are talking a fair bit about sensitivity and specificity this day with COVID testing. This is an excellent reminder!)

Clinical History

• Acute abdominal pain (92%), usually precedes the onset of nausea/emesis
• Nausea 
• Emesis (82%-- more common than nausea)
• Abdominal distention

Risk factors

• Prior abdominal or pelvic surgery (even a simple appendicitis many years ago)
• Abdominal wall or groin hernia (even internal hernia)
• IBD
• Prior irradiation of the abdomen

Physical exam

• Dehydration (even if not apparent on labs), often notable on physical exam (dry mucous membrane, decreased skin turgor)
• Abdominal distention (most important finding on exam)
• Surgical scars
• Tympanic abdomen
• High pitched bowel sounds or more commonly a rush of bowel sounds

Labs

• Leukocytosis is common
• Electrolyte abnormalities (hyperNa, hypoK)
• Lactate is helpful. It's extremely SENSITIVE 90-100%, Specificity 40-80%. This means that a positive lactate gives high likelihood of surgical SBO, but a normal lactate does not rule out an SBO

Imaging: "Everything in SBO comes down to imaging"

• Plain film (KUB): not very specific or sensitive (equivocal 20-30% of the time, misleading in 10-20%), consider skipping it and going straight to the CT
• CT with IV contrast (+oral contrast if possible-- oral contrast commits patient to 4 hours in the ER, often get get enough info with just IV contrast), 
• >90% sensitive, 95% specific. So you can pretty much trust the CT. 
• If the radiologist sees it, it's there. If the radiologist doesn't see it, it's not there.
• CT can usually tell grade, severity and even etiology (adhesion vs. malignancy)
• However, intra-operative location is only correct 60-70% of the time
• MRI (if CT contraindicated, e.g. pregnancy)

Surgical vs. Non-surgical Management:

Patients with SBO should be evaluated for surgical intervention WHEN/IF they are acutely ill with fever, leukocytosis, tachycardia, metabolic acidosis, ongoing pain.

HOWEVER, without the above findings (or with only a few of them) MOST patients should undergo initial non-operative management (this includes both partial AND complete SBO). How so?

Management of early/minimal symptom SBO (with Gastrograffin)
For patients who meet these criteria, Dr. Sawyer and team are working on a protocol to be started soon

If patient meets the following criteria:

1) SBO on CT, 2) distention w/o emesis (x8 hours, or at least minimal emesis, only need NGT if emesis), 3) BM in the last 24 hours, 4) minimal leukocytosis (<14), lactate (<4), THEN you can give them a gastrograffin challenge

How do I do a gastrograffin challenge for minimal symptom SBO?

1. Give patient 90cc of full strength gastrograffin (via NGT or PO);  order from pharmacy (not radiology)
2. Wait 6-8 hours for BM (up to 24 hours). If they have plenty of BMs, they passed! You don't even need to do KUB
3. If no stool in 8 hours, get KUB to look for gastrograffin. 
4. If it has made it to the colon, can pull NGT, start clear liquids and probably let them go home. 
5. If no contrast in cecum, repeat KUB next day. If in the colon, start clear liquids. If not, call surgery.

How does gastrograffin work? For this purpose, it is actually being used therapeutically (rather than diagnostically). Gastrograffin pulls fluid into the lumen and "flushes things through", decreasing the bowel wall edema and improving the SBO.

Who NOT to give gastrograffin challenge to? 

• infection (e.g. appendicitis, diverticulitis)
• cancer
• incarcerated hernia
• pregnancy
• abdominal surgery in last 6 weeks

Prevention of SBO:

There is not great data on any intervention or product done intraoperatively to prevent adhesions and prevent SBO. However, if a patient has had a first episode of SBO or recurrent SBO, Dr. Sawyer recommends:

• low fat diet (maintains intestinal transit time)
• clear liquids are tolerated well (4-6 days): patients with SBO do not need to go home on a regular diet, once a patient feels true hunger, it's time to eat

Recurrence

• 20% recurrence after first episode
• after 3 episodes, their risk of recurrence is greater than 80%, need to consider surgery to lyse adhesions (depending on interval between the recurrences)