Is a bowel prep necessary before colostomy reversal?

Another paper that supports omitting bowel preps before pediatric bowel operations came out in this month’s issue of JPS. In this study, the authors conducted a retrospective, multi-institution study and compared the outcome of 272 children who underwent colostomy reversal with and without (187 vs. 85) a polyethylene glycol bowel prep.

The authors noted a significantly higher rate of wound infection (14.4% vs. 5.8%), as well as a longer hospital stay (5.6% vs. 4.4%) in the group who underwent a bowel prep. Additionally, they noted that the risk for other complications such as abdominal abscess formation (~1%) and ansastomotic leak (~1%) was the same whether a bowel prep was used or not.

Reasons given for the potential deleterious effects of the bowel prep included the characteristics of liquid stool (bowel prep) that make it more difficult to contain, the fact that the bacterial load in prep’d stool is not necessarily lower than unprepped stool (papers sited), and the potential harmful effect of the bowel prep on the integrity of the bowel mucosa.

As with all retrospective studies, the authors acknowledged the limitations of their results, but stressed that, except for intra-pelvic rectal surgery, a bowel prep is likely unnecessary for colonic surgery in children.

Reference:
Serrurier K et al. A multicenter evaluation of the role of mechanical bowel preparation in pediatric colostomy takedown. JPS (2012);47:190-193

Vascular lesions: time to abandon the nomenclature of edibles!

After a long conversation discussing the management plan for a “giant cavernous hemangioma” of the liver, and although I had just recently brushed up on the subject of vascular lesions, I had to go back and look it up again. I was pretty sure the term “cavernous hemangioma” was as antiquated as “strawberry hemangioma” or “port wine stain”; the generalized agreement around me on the diagnosis made me doubts myself. Back to the books.

Sure enough, as of 25 years ago, the International Society on the Study of Vascular Lesions adopted the Mulliken system of classification, which divides vascular lesions into tumors (mainly infantile hemangiomas) and malformations (capillary, venous, lymphatic malformations etc…). This division is based on clinical and histologic characteristics; vascular tumors display endothelial proliferation and usually regress with time, while vascular malformations have a quiescent epithelium, result from dysmorphogensis of vessels, and tend to enlarge with time.

No more should the term lymphangioma, which by vertue of the –oma suffix suggests a tumor, be used to describe a lesion that is a malformation (lymphatic malformation). Nor should the term cavernous hemangioma be used to describe what could either be a deep visceral hemangioma or a venous malformation (two distinct entities, treated in very different ways).

A study by Hassanein et al reviewed articles on vascular lesions and noted a 70% incidence of incorrect nomenclature and a subsequent 20% incidence of incorrect treatment based on erroneous classification. They commented that this is probably an underestimation of the incidence of incorrect diagnosis and treatment in clinical practice, given that experts had probably edited many of these articles for accuracy.

Another reason we should continue to read, read, and read some more.

Reference:
Hassanein et al. Evaluation of terminology for vascular anomalies in current literature. Plastic and Reconstructive Surgery (2011);127(1):347

What is the normal length of small bowel in a preemie?

After informing a dad that his preemie baby has only 45 cm of small bowel left after surgery for NEC, he asked me a question that caught me off guard.
“So how much should he have at 27 weeks gestation?”
Knowing that the small bowel almost doubles in length at the last trimester, I estimated 100 cm’s but then headed back to the books/PDF files to figure out a more exact answer.

Fortunately, there had been some back and forth emails between two of my attendings about papers that looked into expected bowel lengths for preemies.
Went home, pulled the emails out of my ‘Educational’ folder in ‘Mail’, transferred the PDF’s to my ‘Papers’ software, synced my MBP with my iPad (go paperless!), then read the articles during my 45 post-call spin session.

In the first article (via Dr Philip Glick), by Touloukian et al, the authors measured the length of small bowel obtained from autopsy specimens of 30 babies of various gestational ages. The authors documented the bowel length over three age ranges and noted that the small bowel more than doubled its length during the third trimester. As attractive as this article is in its simplicity, several confounding factors, including the fact that post mortem changes may affect the measured length of bowel, limit the accuracy of these bowel measurements.

In the second article, published more than 30 years later (via Dr Doruk Ozgediz), by Strujis et al, the authors obtained intraoperative measurements of small bowel in 108 patients whose post conceptual age ranged from 24 weeks to 5 years. The authors linked the bowel length to gestational age, weight, and patient length at time of surgery. They noted that all three variables predicted the length of bowel with similar accuracy, and suggested that patient height be used since it is more consistent and easier to measure.

Why is this important? Knowing the expected normal length of bowel in a preemie baby makes estimations of the potential risk of short gut syndrome and other outcomes, after intestinal resection, easier; this helps better council parents. It also helps answer the question: "Well, how much bowel should my baby normally have?”

References:
1. Touloukian RJ, et al. Normal intestinal length in preterm infants. Journal of Pediatric Surgery (1983) 18(6):720
2. Strujis M, et al. Establishing norms for intestinal length in children. Journal of Pediatric Surgery (2009) 44:933

Take notes in the OR

At the pediatric surgery residents’ meeting at the AAP last week, one of the speakers, a new graduate who was scheduled to discuss strategies for negotiating an academic job, started off with completely unrelated, but precious advice for residents: read about your patients (and don’t just study for the boards), go to clinic (many pilomatrixomas will be seen in your office), and take notes in the OR. How is it that, as residents, many of us go through training without ever documenting, in our own words, what we are taught in the OR?!

I’m not sure whom I should give credit to for giving me this same advice at the time, but I have been taking notes in the OR since I was a third year resident. And when I say notes, I mean detailed accounts of the main steps, instruments used, suture etc…. I have two notebooks, one from general surgery residency and one from my current pediatric surgery training, filled with elaborate step-by-step instructions. Details about specific preoperative studies, how to prep and drape (attending specific!), exact instruments to use and at what point to switch, post operative management pathways, and follow up plans.

Writing notes helped me focus on and analyze the steps of an operation. I frequently found myself unsure of which step came first or which retractor was used for a specific exposure. The more notes I wrote, the more I paid attention to details I had missed before. I even found myself watching an operation just to be able to fill gaps in my operative notes when there was a step I could not recall.

When I started taking notes and reviewing them preoperatively during my general surgery training, I could not help but notice how positively my attendings reacted to the fact that I prep’d and draped EXACTLY as they did (detailed notes!). Prep right, ask for the exact suture and instrument, and you would be amazed how much more autonomy you may be given.

Those little gems that are mentioned in the OR that you cannot find in any textbook, many of which are the culmination of years of experience, should all be jotted down on the margins of the page next to the detailed list of steps.
“This is where you need to slow down and take your time along this corner, and switch the traction with your left hand to help with exposure” is not something you can find in an atlas, but something that should be written in permanent black ink next to a sketch or diagram.

Unlike a surgical atlas, my own account of how I learned to do a Nissen or a hernia repair will be much more relevant and useful to me when the time comes for me to do the same operation and ask for the next suture or retractor. There will be no time spent scratching my head when the scrub tech asks me what suture I want to close the diaphragmatic defect with or figure out what size clip I need for the PDA ligation. If I had not been taking notes, I might have not remembered that there was such a thing as a M-L clip (green); a clip that is smaller than the Large (orange) which can be too large, and larger than the Medium (blue) that can be too small. Something that would be great to know ahead of time when a preemie’s chest is open and no clip seems to be the correct size!

As a bonus, at the end of my general surgery residency, I asked my favorite attendings to review the notes I took of their operations, correct them as they wished, and sign them as a souvenir. Now, on my bookshelf, I have two of my most precious references and souvenirs from training. I guard them with my life!

What is the 'leading edge' of a transition zone in Hirschsprung's disease, and why is it important?

Time to dip into the old stash for an interesting paper. This one was out of St Louis, MO and looked at the properties of the transition zone of ganglion cells in HD by taking sequential cross sections of surgical specimens and quantifying the ganglion cells in the submucosal and myenteric plexus.

The authors noted that the transition zone was not uniform, but instead had a leading edge (analogous to dripping paint). This leading edge of the transition zone was measured to be up to 2.1 cm (average 1.1 cm) and 2.4 cm (average 1.4 cm) long in the submucosal and myenteric plexuses, respectively. Additionally, the number of ganglion cells at the tip of the leading edge was normal.

The significance of this finding is that a frozen section biopsy performed at the transition zone may result in a pull-through that includes abnormal bowel and potentially poor functional results. The authors thus recommended that a pull-through be performed using bowel that is at least 2 cm proximal to the area of 'normal' ganglionated bowel identified intraoperatively by frozen section

Reference:
White et al. Circumferential distribution of ganglion cells in the transition zone of children with Hirschsprung's disease. Pediatric and Developemental Pathology (2000) 3, 216

What to do with a child in the ED after a household electrocution?

So a kid gets bounced around hospitals before being sent to our ED for admission. Shortly after, we send the kiddo home with some local wound care to a blister.

Low voltage electrocution (<1000 volts) is a common household injury that is usually a result of contact with electric cords and wall outlets. One of the main concerns with electrocution is related to cardiac consequences, specifically ventricular fibrillation and direct myocardial injury.

Chen et al reviewed the literature pertaining to the management and outcome of children exposed to a low voltage current (usually household appliances with a maximal voltage of 240V). They summarized the results of 7 retrospective studies that evaluated the relationship between the type of voltage, patients symptomatology at the scene (cardiac arrest, ventricular fibrillation), EKG findings (when an EKG was performed), and patient outcome.

The upshot of the review article was that healthy children who are exposed to household currents, when asymptomatic at the field and in the ED, had a very low risk of developing cardiac arrhythmias. When the children did have 'benign' arrhythmias (mainly sinus tacchycardia, vernticular premature complexes, and premature junctional complexes), those resolved spontaneously. Children who did not have abnormal EKG findings never developed any late arrhythmias.

The authors concluded that it is safe to discharge asymptomatic children exposed to household currents without and EKG or telemetry.

Reference:
Chen EH, Amit S. Do children require ECG evaluation and inpatient telemetry after household electrical exposure. Annals of Emergency Medicine 2007;49:64-67

Pediatric Liver Tumors Power Notes [1]

What is the age range of children with hepatoblastoma (HB) vs. hepatocellular carcinoma (HCC)?
HB is most common between the ages of 6 months and 3 years, while HCC occurs in older children and adolescents.

What is the origin of HB?
HB arises from pluripotent hepatic stem cells or oval cells that can differentiate into hepatocytes or biliary epithelial cells.

What conditions is HB associated with?
Beckwith-Wiedemann syndrome
Hemihypertrophy
Low birth weight
FAP

What proportion of liver tumors are malignant?
2/3

What % of patients with HB have thrombocytosis?
60%

What is the most sensitive blood test to evaluate for HB and HCC?
AFP: produced by fetal liver cells and yolk sac. In neonates, levels are normally elevated and then drop to adult levels by age 6 months.
AFP is elevated in 90% of children with HB, and 70% of those with HCC
AFP levels are not associated with the level of maturity of HB

What other conditions cause elevated AFP levels?
Liver cirrhosis
Hepatitis
Germ cell tumors
Hemangioendothelioma
Testicular tumors
Gall bladder CA

Which variant of HCC is not associated with elevated AFP levels?
Fibrolamellar HCC

What should we look for when imaging for liver tumors?
Size/location of tumor
Metastatic disease
Vascular invasion to PV, HV, and VC

What is the advantage or MRI?
MRI is accurate in determining the relationship of the tumor to vascular and biliary structures.
Tumors appear homogenous and hypointense on T1 sequences, and hyperintense on T2 sequences.

Is FNA biopsy an option with liver tumors.
Yes, FNA may be sufficient to confirm the diagnosis.

What are the benign liver tumors?
Benign vascular tumors
Mesenchymal hamartoma
Adenomas
FNH

What is the role of HB histology in prognosis?
The histology of HB has minimal impact on prognosis.

What is the histologic classification of HB?
Epithelial vs. mixed (epithelial + others)
Epithelial divided into: Fetal, embryonal, macrotunular, and small cell undifferentiated.

What from of HCC has a better outcome than the typical variants?
Fibrolamellar variant

What is the COG staging system based on?
Post resection extent of disease.
Stage !: completely resected. Purely fetal histology (PFH) with minimal mitotic figures is unique group
Stage 2: microscopic residual disaese
Stage 3: gross residual disease
Stage 4: metastatic disease

What is unique about the PFH group?
When completely resected, patients with PFH and low mitotic figures (<2/10 mitotic figures) have excellent outcomes and do not require adjuvant chemotherapy. This situation occurs in 5% of patients with HB. What are factors that can compromise surgical resection?
Multifocality, bilobar involvement, portal vein or vena cava thrombosis, para-aortic lymphadenopathy, extension into liver hilum, and metastatic disease.

Why should a smaller incision be used initially?
A smaller incision should be used first to assess resectability before committing to a larger incision.

How should microscopically positive margins be managed?
Re-excision if possible.

Why should intraoperative U/S be used?
Intraoperative U/S should be used to better assess vascular involvement.
The most common cause of complications such as positive resection margins, severe intraoperative hemorrhage, and post operative liver failure secondary to Budd Chiari syndrome is unrecognized involvement of the remaining solitary hepatic vein.

What are options for anatomic resection?
R or L hepatic lobectomy
Extended R or L hepatic lobectomy
Central resection
Segmental based anatomic resection (rare)

What are the basic steps for resection?
Check for metastatic disease
Mobilize liver
Dissect poratal structures
Ligates structures supplying intended segment of liver to create line of demarcation
Dissect VC off the liver towards the VC, leaving hepatic veins as only attachment
Ligate hepatic veins within parenchyma of liver vs. extra-hepatic segments.
Perform parenchymal dissection

What is the max time allowed for clamping of portal structures?
60 minutes total, 15 minutes at a time.

What is the name of the imaginary line between GB and IVC?
Median portal fissure.

How much of the liver is removed with a L lobectomy vs a R lobectomy?
A L lobectomy removes 35% of liver parenchyma while a R lobectomy removes 65%.

What are potential postoperative complications?
Bleeding, subphrenic abscess, biliary fistula, wound infection, and biliary obstruction.
Perioperative mortality is 5%.

Why are neonates more susceptible to complications of liver resection and how is that counteracted?
Neonates have immature livers and are susceptible to postoperative hypoalbuminemia, hypoglycemia, and hypothrombinemia.
Perioperative administration of vitamin K, albumin, and vitamin K can counteract these deficiencies.

what % of HB will require liver transplant?
6%

What is the contra-indication to liver transplant in HB?
Extrahepatic disease

What are 10-year survival rates after primary transplant vs. rescue transplant (after attempted resection)?
Primary transplant has 85% 10-year survival, vs. 30-50% with rescue transplant.

When is transplant indicated for HCC?
Single lesion <5cm or up to three nodules < 3 cm. What are the disadvantages of neo-adjuvant chemotherapy?
Non-responders may experience disease progression.

What are agents used for initial therapy vs therapy for non-responders/recurrent disease?
Baseline therapy is with Cisplatin/Vincristine/5-FU or Cisplatin/Doxorubicin.
Resistant or recurrent disease is treated with etoposide/carboplatin or irinotecan

How often are unresectable tumors rendered resectable by neo-adjuvant therapy?
up to 70% of stage 3 tumors become resectable with neo-adjuvant therapy.
Only 30% of HCC are rendered resectable with neo-adjuvant therapy.

What is the role of radiation in liver tumors?
Radiation has a limited role. Not very effective.

What is suicide gene therapy?
Therapy that selectively targets tumor cells, where a non-toxic, cell permeable pro-drug, is converted to a toxic drug inside tumor cells only.

What are available options for ablative therapy?
Patients who are not candidates for transplant or resection can undergo ablative therapy.
Options incllude:
1. Chemo-embolization
2. RFA: Needle electrode delivers heat through an alternating current
3. Percutaneous injection of alcohol
4. Cryoablation: direct freezing then thawing results in cell death.

What are U/S findings that help guide ablative therapy?
RFA: echogenic micro-bubbles delineate the zone of therapy
Cryoablation: echogenic expanding rim

What is 5 year survival of HB vs HCC?
75% for HB vs 30% for HCC

What is 5 year survival with successful resection?
up to 100% for HB vs 54% for HCC

What is the primary predictor of poor prognosis?
Metastatic disease

What is the role of lung metastectomy?
Only lung lesions that do not respond to neoadjuvant chemotherapy should be resected

Reference:
1. Grosfeld's Pediatirc Surgery. Sixth edition. Chapter 30. Liver Tumors