View source for Medicine:Subungual hematoma

{{Infobox medical condition (new)
| name            = Subungual hematoma
| synonyms        = Runner's toe, tennis toe, skier's toe
| image           = Subungal hematoma of the finger.jpg
| caption         = Subungal haematoma of the fourth finger
| pronounce       = 
| field           = Internal medicine, Podiatry
| symptoms        = Discoloration of nail, pain
| complications   = 
| onset           = 
| duration        = 
| types           = 
| causes          = 
| risks           = Poorly fitting foot wear, [[Medicine:Overtraining|overtraining]] particularly hiking and [[Biology:Running|running]] 
| diagnosis       = 
| differential    = 
| prevention      = 
| treatment       = Usually unmerited, [[Biology:Blood|blood]] drainage or nail removal in serious cases
| medication      = 
| prognosis       = Usually self-resolving as nail grows out
| frequency       = 
| deaths          = 
}}
[[File:Hematomasubungual.png|thumb|Subungal haematoma of a toe]]

A '''subungual hematoma''' is a collection of [[Biology:Blood|blood]] (hematoma) underneath a toenail or fingernail. It can be extremely painful for an injury of its size, although otherwise it is not a serious medical condition.

==Nature==
A [[Medicine:Wound|laceration]] of the nail bed causes bleeding into the constricted area underneath the hard nail plate.<ref>{{cite book |vauthors=Selbst SM, Attia M |title=Textbook Of Pediatric Emergency Medicine |publisher=Lippincott Williams & Wilkins |location=Hagerstown, MD |year=2006 |isbn=978-0-7817-5074-5 |page=1571 |chapter=Lacerations}}</ref>  The blood pools under the nail, giving a reddish, brownish, blueish, or grey/blackish discoloration. The blood puts pressure to the nailbed causing pain which can be throbbing in quality and disappears when the pressure on the nail bed is relieved.<ref>{{Cite book|url=https://www.ncbi.nlm.nih.gov/books/NBK482508/ |title = Subungual Hematoma Drainage - StatPearls - NCBI Bookshelf| year=2022 | pmid=29494114 | last1=Pingel | first1=C. | last2=McDowell | first2=C. | chapter=Subungual Hematoma Drainage | publisher=StatPearls }}</ref>

Subungual hematomas typically heal without incident, though [[Medicine:Infection|infection]] may occur. The pressure of the blood blister may cause separation of nail plate from the nail bed (onycholysis), but the nail should not be pulled off, as this can cause scarring of the nailbed and deformed nails.<ref name=cleveland>{{cite web |title=3 Tips to Protect Your Toenails If You're a Hard-Core Runner |url=https://health.clevelandclinic.org/3-tips-protect-toenails-youre-hard-core-runner/ |website=Health Essentials from Cleveland Clinic |date=3 December 2015}}</ref> Nail discolouration may last some months.<ref name=marathon/>

The nail plate may also become thicker and more brittle as a result of the injury (onychochauxis). The deformed nail plate will gradually grow out and be replaced by new, normal-appearing nail plate in several months' time. Infrequently, the nail may become painful and require surgical drainage.<ref name=statpearls>{{cite journal |last1=Pingel |first1=C |last2=McDowell |first2=C |title=Subungual Hematoma Drainage |date=January 2019 |pmid=29494114 |journal=StatPearls [Internet] |url=https://www.ncbi.nlm.nih.gov/books/NBK482508/}}</ref>

==Causes==
[[File:Preventing black toenail subungual hematoma.svg|thumb|left|Right: Shoe is loose, slides. Center: Too little ease for foot to extend. Left: Proper fit]]
[[File:Runners_toe.jpg|thumb|A foot which has lost a toenail, due to running injuries exacerbated by poorly-fitting shoes, badly-cut nails, and mild Morton's toe]]

The condition is caused by a traumatic injury, such as slamming a finger in a door,<ref>{{cite web |title=Subungual Hematoma: Care Instructions |url=https://myhealth.alberta.ca/Health/aftercareinformation/pages/conditions.aspx?hwid=zc1301 |website=myhealth.alberta.ca}}</ref> or from sports activities, especially those involving sudden accelerations, such as soccer, basketball, and tennis,  or going downhill, such as running or hiking rugged terrain, and ill-fitting footwear.<ref name=marathon/><ref name=cleveland/><ref name=usmilit />{{rp|52,135}}

Repeatedly thrusting the toes against a shoe's toe box can cause a subungual hematoma called jogger's toe,<ref>{{cite journal |pages=498–501 |doi=10.1136/bjsm.2004.011874 |title=The wear and tear of 26.2: dermatological injuries reported on marathon day |year=2004 |last1=Mailler |first1=E A |journal=British Journal of Sports Medicine |volume=38 |issue=4 |pmid=15273194 |last2=Adams |first2=BB |pmc=1724877}}</ref> runner's toe, or black toenail. In a marathon, several percent of [[Biology:Running|runners]] may be affected.<ref name=marathon/> Wearing footwear which fits helps prevent runner's toe.<ref name=marathon/>

If the shoe is too loose on the midfoot, the foot can slide forwards in the shoe, especially when going downhill. This may jam the toes into the end of the toebox.<ref name=marathon/> If the foot is sliding forwards because the shoe is too loose around the midfoot, it may be restrained by lacing the shoe carefully, or placing bulky padding between the tongue and the lacing, or by wrapping a strap in a figure-eight around the foot and ankle ([[:File:Soldiersfootmili00munsrich Fig53 Marching strap of the French army (for avoiding joggers toe).png|image]]).<ref name=usmilit />{{rp|86–87,128,142}} Excessively tight or uneven fit around the midfoot may, however, cause tendon problems.<ref name=usmilit />{{rp|125}}{{better source|date=January 2020}}

Separately, if there is not enough space around the toes, the toes will also hit the toebox repeatedly.<ref name=marathon/> Feet become longer and wider when weight is put on them, because the arches flatten, and the toes also splay and bend.<ref name=usmilit>{{cite book |last1=Munson |first1=Edward Lyman |title=The soldier's foot and the military shoe; a handbook for officers and noncommissioned officers of the line |date=1912 |location=Menasha, Wis.|publisher=Press of the George Banta publishing company |url=https://archive.org/details/soldiersfootmili00munsrich}} (this is the publication of a four-year review into the footwear of the US military by the Army Shoe Board, of which the author, a physician and senior officer of the United States Army Medical Corps, is president.</ref>{{rp|p15,18,72–73}} At the end of a long journey on foot, the arches flatten, the metatarsals spread, and the foot swells more than after a short one.<ref name=usmilit />{{rp|52}} The toes also need vertical space; a toe cap which is low enough to press on the top of the toe may also cause bruising under the nail, especially if the toe cap is stiff. If the toebox is pointed, the toes may be wedged forwards into the area with inadequate height.<ref name=usmilit />{{rp|52–53,135}}

Toenails which protrude unevenly may concentrate force on the toenail; properly-cut nails are therefore also important.<ref name=marathon>{{cite journal |last1=Mailler |first1=EA |last2=Adams |first2=BB |title=The wear and tear of 26.2: dermatological injuries reported on marathon day. |journal=British Journal of Sports Medicine |date=August 2004 |volume=38 |issue=4 |pages=498–501 |doi=10.1136/bjsm.2004.011874 |pmid=15273194 |pmc=1724877 }}</ref>

Some susceptible runners may also have [[Medicine:Morton's toe|Morton's toe]]. In this variant of human foot anatomy, the second toe extends further out than the great toe. This can make it harder to find shoes with adequate space around the toes.{{citation needed|date=January 2020}}

==Treatment==
Subungual hematomas can resolve on their own, without treatment being necessary.<ref name=marathon/> If they are acutely painful,<ref name=2012_review>{{cite journal |last1=Dean |first1=B |last2=Becker |first2=G |last3=Little |first3=C |title=The management of the acute traumatic subungual haematoma: a systematic review |journal=Hand Surgery |date=2012 |volume=17 |issue=1 |pages=151–4 |doi=10.1142/S021881041230001X |pmid=22351556}}</ref> they may be drained.<ref name=statpearls />

Subungual hematomas are treated by either making a hole through the nail into the hematoma (trephining) within 48 hours of injury, draining the blood and releasing the pressure,<ref name=statpearls/> or, less conservatively, by removing the entire nail.<ref>{{cite web|author=<!--Staff writer(s); no by-line.-->|title=Primary Care Procedures: Trephination of Subungual Hematoma|url=http://www.consultantlive.com/skin-diseases/primary-care-procedures-trephination-subungual-hematoma|archive-url=https://web.archive.org/web/20160821165953/http://www.consultantlive.com/skin-diseases/primary-care-procedures-trephination-subungual-hematoma|archive-date=21 August 2016|access-date=30 July 2016|website=consultantlive|publisher=UBM Medica, LLC}}</ref> 

In a hospital or medical setting, trephining is generally accomplished by using an electrocautery device or an 18-gauge needle. The hole is covered with sterile dressing and must be kept dry afterwards.<ref name=statpearls />

Removal of the nail is typically done when the nail itself is disrupted, a large laceration requiring [[Medicine:Surgical suture|suturing]] is suspected, or a fracture of the tip of the finger occurs.  Although general [[Medicine:Anesthesia|anesthesia]] is generally not required, a digital nerve block is recommended if the nail is to be removed.{{citation needed|date=January 2020}} For trephination, the block is often more painful than the procedure.<ref name=statpearls/>

Complication rates from both forms of treatment are low, and the nail generally recovers to a normal appearance.<ref name=2012_review/>

== See also ==
{{Commons|Category:Subungual hematoma of finger|Subungual hematoma of finger}}
* List of cutaneous conditions
* [[Medicine:Metatarsophalangeal joint sprain|Turf toe]]

== References ==
{{Reflist}}

== External links ==
{{Medical resources
|  DiseasesDB     = 
|  MeshID         =
 | ICD10          = {{ICD10|L|60|8|l|60}} (ILDS L60.872)
 | ICD9           = {{ICD9|924.3}}, {{ICD9|923.3}}
 | ICDO           =
 | OMIM           =
 | MedlinePlus    =
 | eMedicineSubj  = article
 | eMedicineTopic = 827104
 | eMedicine_mult = {{eMedicine2|article|82926}}
}}
{{General injuries}}

[[Category:Foot diseases]]

{{Sourceattribution|Subungual hematoma}}